Get quick answers to frequently asked questions about Breast Cancer. Learn more and find out what actions you can take to reduce your breast cancer risk and put prevention first.
Q1. What is breast cancer?
Breast cancer is cancer that starts in breast tissue. It begins when abnormal cells in the breast grow uncontrolled and eventually form a growth (tumour). Breast cancer occurs when breast tumours spread. There is generally a long period between breast tissue changes and the development of breast cancer.
Breast cancer is a diverse group of diseases which occurs in both men and women, although it is much less common in men.
Q2. How common is breast cancer?
Breast cancer is the most common cancer in the world. In the UK, approximately 56,000 women and 400 men are diagnosed with breast cancer every year. It’s estimated that 1 in 7 women and 1 in 870 men will develop breast cancer in their lifetimes.
Q3. What are the most common types of breast cancer
Breast cancer is a diverse group of diseases. The most common types of invasive breast cancer include invasive breast cancer of no special type (NST), also called invasive ductal carcinoma, which accounts for 70% of all invasive breast cancers in women and over 90% in men. Invasive lobular breast cancer accounts for around 15% of breast cancers in women but is extremely rare in men. Less common types include inflammatory breast cancer and Paget’s disease of the breast.
Breast cancers are classified into subtypes according to hormone receptor status. Hormone receptor-positive breast cancers have additional receptors for oestrogen, progesterone and/or human epithelial growth factor 2 (HER2). Oestrogen receptor-positive breast cancer accounts for around 80% of all breast cancer cases. Triple-negative breast cancer has no additional receptors and accounts for around 15% of female breast cancers. Non-invasive breast cancer is an early form of breast cancer which remains localised to the breast. The most common form is ductal carcinoma in situ (DCIS) which can occur in both men and women.
Q4. What are the symptoms of breast cancer?
Breast cancer symptoms include:
9 out of 10 breast lumps are completely harmless. But if you spot any of these symptoms, we recommend contacting your GP.
For more information on how to check your breasts visit our breast check resource and sign up for our free monthly text reminder.
Q5. What should I do if I think I have breast cancer?
If you notice any symptoms of breast cancer, consult your GP. If they think your symptoms need further assessment, they’ll refer you to a specialist breast cancer clinic for further investigation.
Q6. How is breast cancer diagnosed?
Diagnosis is usually based on the results of a mammogram (breast X-ray) or an ultrasound scan (often used if you are under 35 years of age). You may also require a biopsy. A breast biopsy is where a sample of cells is taken from your breast and examined under a microscope to see if abnormal or cancerous cells are present.
Other investigations, such as a CT scan, may also be required before deciding on treatment.
In some cases, you may also be offered a mammogram with contrast (also called contrast-enhanced spectral mammography). This type of mammogram involves injecting contrast material into your veins which allows cancers to be detected more easily on a mammogram. This scan is not currently part of the breast screening pathway but is sometimes offered to patients whose mammograms are inconclusive. Some hospitals are now trialling this new technology to help detect breast cancer sooner.
Q7. What are the causes of breast cancer?
The causes of breast cancer are not fully understood. However, studies have identified numerous factors which increase breast cancer risk (known as “risk factors”), including those associated with age, genetics, circulating hormone levels, lifestyle, diet and environmental factors. Some of these factors you can influence, whilst others you have no control over.
For more information, please visit our prevention hub.
Q1. Is being overweight a breast cancer risk?
Being overweight when women have reached menopause is a significant risk factor for breast cancer. It is also a risk factor for men.
Q2. Does being overweight or obese increase the risk of breast cancer in premenopausal women?
Despite increasing the risk of breast cancer in postmenopausal women, there is no evidence that being overweight when pre-menopausal is associated with increased risk of breast cancer.
However, young women should not intentionally gain weight to lower their breast cancer risk. Some studies suggest that obese premenopausal women who get breast cancer have more aggressive subtypes. Putting on weight throughout adulthood increases your risk of developing breast cancer after menopause.
The reasons that being overweight before menopause appears to be protective against breast cancer are not fully understood, although they may relate to oestrogen production, which is mainly produced by the ovaries in premenopausal women and by fat tissue in women following menopause. In premenopausal women, excess fat tissue affects the functioning of the ovaries, resulting in a reduction in menstrual cycles and, as a result, reduced exposure to sex hormones, including oestrogen. After menopause, excess fat tissue increases levels of circulating oestrogens, which increases your breast cancer risk.
It should also be noted that many endocrine disrupting chemicals (EDCs) are fat-soluble and can be stored in fat cells. Certain EDCs may increase breast cancer risk (for more information about EDCs and breast cancer, see here). Finally, many health risks are associated with being overweight or obese, so it is important for women to maintain a healthy weight throughout life.
Q3. Is there a link between eating processed meat and breast cancer?
There is convincing evidence that increased consumption of processed meats, such as bacon and salami, slightly increases breast cancer risk.
Q4. Can a healthy diet help to prevent breast cancer?
Having a healthy diet can help prevent breast cancer.
Healthy eating includes:
For further information, please visit our Everyday Life IGuide.
Q5. Does drinking alcohol increase my breast cancer risk?
Drinking alcoholic beverages increases the risk of breast cancer in women, and heavy drinking increases the risk in men. The more alcohol a woman consumes, the greater the risk, with no lower threshold.
Q6. What is the ideal diet to decrease my risk of breast cancer?
There is no ideal diet for breast cancer prevention; rather, it is more important to pay attention to the proportions of different food groups you consume. Many diets can be healthy and help reduce your risk, including the Mediterranean diet and balanced vegetarian diets. They all combine certain basic features, for example, no or low red meat consumption and a high proportion of fruit and vegetables.
Q7. Does eating a vegan or vegetarian diet decrease breast cancer risk?
There is insufficient evidence to be certain that vegetarians or vegans have a lower risk of developing breast cancer. However, many of the foods and eating patterns that make up a healthy vegan or vegetarian diet have been shown to reduce breast cancer risk, for example, eating lots of fruits and non-starchy vegetables, replacing meat with plant-based protein sources like tofu, nuts, and legumes, and eating some dairy or dairy alternatives which provide calcium.
A vegetarian or vegan diet can also help keep a healthy weight or help those who need to lose weight, which is important for breast cancer prevention. Healthy foods eaten as part of a vegetarian or vegan diet are rich in fibre and tend to be lower in calories, fat, and protein compared to animal foods.
However, the benefits of vegetarianism or veganism largely depend on the types of foods you eat and your overall dietary habits. Whilst many processed vegetarian/vegan foods are a good source of fibre and protein, some may also contain additives, stabilisers and enhancers to make them taste more like meat, which can make them a less healthy option. We recommend looking over ingredient lists.
Q8. Does eating organic food decrease my risk of getting breast cancer?
The few human studies that have investigated the effects of organic food on breast cancer risk have so far yielded mixed results. However, eating organic food decreases pesticide exposure, and exposure to certain pesticides may increase breast cancer risk. Examples include the insecticide malathion and the herbicide glyphosate. Pesticides and herbicides may act as mammary carcinogens or increase breast cancer risk by disrupting hormones, especially oestrogen.
The Dirty Dozen represents lists of conventionally grown fruits and vegetables with the highest pesticide residues. It is based on PAN UK’s analysis of the UK government’s pesticide residue testing programme.
Q9. Does drinking cow’s milk increase breast cancer risk?
There is insufficient evidence to conclude that drinking cow’s milk increases or decreases breast cancer risk. Evidence from several meta-analyses suggests that a diet high in milk does not affect breast cancer risk. A few meta-analyses suggest dairy products may reduce pre-menopausal breast cancer risk and have no effect on risk for women after menopause. Some observational studies found that a diet high in cow’s milk increases risk. Some find the opposite, whilst many others conclude cow’s milk does not alter risk.
Dairy products contain both calcium and vitamin D, which are protective against breast cancer.
Concerns that milk increases risk stem from the fact that cow’s milk usually comes from pregnant cows and contains high levels of bovine hormones, including bovine oestrogen. Drinking cow’s milk containing high levels of this hormone increases levels of human insulin growth factor 1 (IGF-1), and women with higher levels of IGF-1 have a slightly increased breast cancer risk. More research is needed to understand the impact of drinking cow’s milk on breast cancer risk.
Q10. Can vitamin D supplements reduce my breast cancer risk?
Despite a link between low levels of vitamin D and increased breast cancer risk, most studies do not demonstrate that taking vitamin D supplements reduces breast cancer risk. The reasons for this are unclear, and more studies are needed to confirm this finding. However, taking them can restore circulating vitamin D levels to a healthy state and is recommended for people unable to achieve sufficiency through sunshine and diet.
Q11. Does consuming too much sugar increase breast cancer risk?
There is insufficient evidence to conclude that a diet high in sugar increases breast cancer risk, although some studies support this.
However, consuming large amounts of sugar can promote weight gain, often without the added benefit of vitamins and minerals, so-called “empty calories,” and being overweight or obese increases the risk of breast cancer in men and postmenopausal women.
Q12. Does consuming products containing artificial sweeteners increase breast cancer risk?
There is currently no strong link between artificial sweeteners and breast cancer risk. A recent study in 2023 identified a link between a higher intake of certain artificial sweeteners (including aspartame) and breast cancer risk. However, more research is required to confirm whether this is a direct association.
In July 2023, the International Agency for Research on Cancer classed the artificial sweetener aspartame as ‘possibly carcinogenic’ (group 2B). This means of the research it has reviewed; it has found limited evidence that aspartame can cause cancer. However, it is recommended to limit the consumption of food and drinks containing artificial sweeteners.
Q12. Does eating soy products increase breast cancer risk?
Eating soy products does not increase breast cancer risk even though soy contains phytoestrogens. On the contrary, several recent studies examining the effects of a soy-rich diet on breast cancer risk found a protective effect from soy and soy-based foods like tofu, but more research is needed to confirm this finding.
Q13. Does physical activity affect my risk of breast cancer?
Physical activity helps to lower breast cancer risk. It also helps prevent recurrence and mortality following a breast cancer diagnosis. Studies suggest being physically active can reduce your risk of breast cancer by around 20%. Any type of additional physical activity is beneficial; the more, the better. We recommend, as a minimum, following the World Health Organisation’s (WHO) guidelines.
Q14: Does smoking increase breast cancer risk?
Smoking is likely to increase breast cancer risk slightly. Most (but not all) studies and meta-analyses conclude there is a modest increase in breast cancer risk for those who smoke, especially for premenopausal women and those who started smoking at a young age.
Q15: Does vaping increase breast cancer risk?
Due to e-cigarettes being a relatively new product, there is currently limited evidence on the link between vaping and breast cancer. E-cigarettes do not contain tobacco, which contains several harmful chemicals and substances. However, they can contain some chemicals at lower levels that have previously been linked to breast cancer risk.
Q1. How might exposure to certain chemicals increase breast cancer risk?
Some chemicals are harmful and can damage our DNA, known as carcinogens. Others may be harmful as they can interfere with our hormones; these are known as endocrine (or hormone) disrupting chemicals (EDCs). Some EDCs can mimic the actions of the natural hormone oestrogen; exposure to high levels of this hormone increases breast cancer risk. Similarly, exposure to compounds that mimic oestrogen may also increase risk.
For further details, visit our Chemicals and the Environment IGuide.
Q2. Where are endocrine-disrupting chemicals found?
Endocrine disrupting chemicals (EDCs) are often found in many everyday products such as cosmetics, kitchenware, plastic bottles, the lining of metal food cans, furniture and furnishings, electronics, toys, pesticides, waterproof clothing and food. They are present in air, soil and water.
They enter your body through eating, drinking, breathing and absorption through your skin.
Q3. Why don’t other cancer charities highlight exposures to harmful chemicals (such as endocrine disrupting chemicals) as breast cancer risk factors?
Most cancer charities choose to prioritise other, more well-established risk factors for breast cancer over exposure to chemicals of concern, including endocrine disrupting chemicals (EDCs). Some charities are not yet convinced that sufficient evidence is available to demonstrate that harmful chemicals, such as EDCs that are oestrogen mimics, increase breast cancer risk. This is due to a lack of research into the effects of harmful chemicals on human health.
Whilst we support the valuable work other cancer charities do, warnings from reputable scientists as well as bodies such as the United Nations Environment Programme, World Health Organisation (WHO) and the Endocrine Society suggest that chemical exposure, particularly to multiple compounds throughout life and at specific life stages does have implications for human health, including potentially increasing the risk of breast cancer.
At Breast Cancer UK, we adopt a precautionary approach. If there is scientific evidence that a chemical has a possible link to breast cancer, we advise avoiding that chemical and calling for its use to be restricted or banned so that everyone is more protected.
Q4. Does drinking water from plastic bottles increase breast cancer risk?
Some types of plastic bottles contain bisphenols (found in polycarbonate plastics; plastic recycling code 7) or phthalates (found in recycled PET, plastic recycling code 1) which may contribute to an increased risk of breast cancer. It is very unlikely that occasional exposure to such chemicals will result in breast cancer development. However, if plastic drink bottles are used repeatedly, especially if heated, these chemicals can leach out into liquids. Long-term exposure to these and other oestrogen mimics may contribute to increased breast cancer risk.
Q5. Do antiperspirants and deodorants increase breast cancer risk?
There is some scientific evidence that endocrine disrupting chemicals (EDCs) found in deodorants and antiperspirants may increase breast cancer risk. Most antiperspirants contain aluminium salts which some scientists believe may increase breast cancer risk. Other types of deodorants contain perfume and anti-microbial agents such as parabens; some of these are EDCs which may also be linked to breast cancer.
Single or infrequent exposure to any EDC is unlikely to increase breast cancer risk. However, long-term exposure to oestrogenic EDCs, such as those found in antiperspirants, may be linked to increased risk.
Q6. Does using products containing lavender oil increase my risk of breast cancer?
To our knowledge, no studies have investigated whether there is an association between lavender oil use and breast cancer risk. Some in vitro studies (experiments done on cells in a lab) have demonstrated that lavender oil has oestrogenic properties similar to some synthetic endocrine disrupting chemicals (EDCs). One small study found an association between the use of products containing lavender and premature breast development in young girls, which may be a risk factor for breast cancer. Regular exposure to lavender oil has also been linked to abnormal breast growth in young boys, known as prepubertal gynecomastia. However, research is still inconclusive. We, therefore, recommend a cautious approach to using lavender-based products.
Q7. How can I tell if personal care products contain endocrine disrupting chemicals (EDCs)?
To identify EDCs found in personal care products, we recommend using the Yuka app, which analyses hygiene and cosmetic products and provides detailed information to help you understand the potential impact on your health. Additionally, if a product scanned gets a bad score, Yuka offers independent recommendations for safer alternatives. The Yuka app can be downloaded here. If you prefer not to use an app, you can also check our list of ingredients to avoid in cosmetics and personal care products. Our A to Z Chemicals of Concern list can also help identify EDCs in consumer products which may be linked to breast cancer.
Q8. What sunscreens should I avoid?
Many suncreams contain various endocrine disrupting chemicals (EDCs), which we recommend you avoid. These include parabens such as propylparaben (used as preservatives) and UV filters (active ingredients), for example, benzophenones (including oxybenzone or benzophenone-3 and avobenzone), octyl methoxycinnamate, octinoxate and padimate O. These ingredients have been linked to breast cancer, as well as environmental damage. We recommend using suncream, which is mineral based and contains as its active ingredient zinc oxide in its non-nano form (nano-form suncreams can be absorbed by the skin and may harm aquatic life). Spray and powder form suncreams should also be avoided due to the risk of inhalation.
Both the Yuka app (see Q5) and our list of ingredients to avoid in cosmetics and personal care products can help in selecting sunscreen.
Q9. Does eating food stored in plastic containers or takeaway boxes increase breast cancer risk?
Many plastic containers and takeaway boxes, including the greaseproof linings of pizza boxes, contain endocrine disrupting chemicals (EDCs) including bisphenols, phthalates and PFAS, which may, affect breast cancer risk in the long-term.
These chemicals can leach from containers/wrapping material into food (and the environment), leading to unintentional human exposures. The leaching process may also be accelerated under certain conditions, including high temperature (e.g., microwaving), high pH (e.g., detergents) and prolonged contact time.
Occasional exposures to EDCs are unlikely to confer an increased breast cancer risk. However, repeated and frequent exposure to synthetic chemicals such as bisphenols, which can mimic the effects of oestrogen, may be a risk factor for breast cancer.
Q10. Can my child be exposed to EDCs in the womb?
Biomonitoring studies have detected various endocrine disrupting chemicals (EDCs) in the placenta, umbilical cord serum of mothers and the urine of unborn children. Furthermore, animal studies have found that exposure to EDCs in the womb (termed ‘in utero’) may increase the risk of breast cancer during adulthood. More studies are required to assess the long-term impact of chemical exposures in utero. You can read our advice for protecting your baby’s health here.
Q11. Does exposure to parabens affect breast cancer risk?
Cell culture studies (those undertaken in a laboratory) suggest that long-term exposure to certain parabens may increase breast cancer risk. Parabens can mimic the actions of oestrogen. They can increase the growth rate of cancerous and non-cancerous breast cells, increase levels of natural oestrogen in breast cells and potentially increase the growth of oestrogen receptor-positive breast cancers. At high concentrations, they promote genotoxicity (damage DNA).
Animal studies have found that propylparaben, at levels relevant to human exposure, can induce long-term alterations to the mammary gland, which may make animals more susceptible to mammary cancer. Methylparaben may reduce the effectiveness of tamoxifen for treating breast cancer.
Parabens have been measured in breast tissue and other body fluids in humans. However, most epidemiological studies have not demonstrated a link between parabens and breast cancer.
Q12. What are microplastics and can they affect breast cancer risk?
Microplastics are defined as plastic pieces that are less than 5mm in size, are insoluble in water and can take centuries to break down completely. Primary microplastics are intentionally made for commercial purposes, such as microbeads in cosmetic products and microfibres in clothing. Secondary microplastics result from the breakdown of larger plastics and are often found polluting land and aquatic environments. These microplastics have been detected in wildlife and in human blood, breast milk and tissues.
There is limited evidence on the link between microplastic exposure and breast cancer risk, yet it is a significant concern for human health. Microplastics may already contain harmful chemicals, but they can also absorb other chemicals and transfer them to the surrounding environment. Many of these chemicals (including bisphenols, PFAS and phthalates) have previously been linked to an increased breast cancer risk.
Q13. What are forever chemicals?
Forever chemicals are per- and polyfluorinated alkyl substances (PFAS) that do not naturally break down in the environment or in our bodies. This can lead to chemical build-up in the human body, which may promote adverse health effects. Some studies have linked some PFAS with an increased risk of breast cancer.
Due to their ability to break down, we can still be exposed to those PFAS that have been banned in consumer products due to their adverse health effects.
Q14. What is an ‘obesogen’?
An obesogen is a chemical compound that can disrupt normal fat metabolism processes and may influence or promote obesity. They may act in the body by increasing the number of fat cells or increasing the storage of existing fat cells.
Obesogens are also endocrine disrupting chemicals (EDCs). Many EDCs have previously been linked to breast cancer risk. The human breast contains a large proportion of fat and many EDCs have been shown to accumulate in breast fat tissue, which could influence breast cancer development.
Q1. Is breast cancer during pregnancy common?
Breast cancer during pregnancy, or pregnancy-associated breast cancer (PABC), is defined as breast cancer diagnosed during pregnancy or in the first postpartum year. It is rare and occurs in around 1 in every 3,000 pregnancies.
Q2. How does age at the birth of a first child affect your breast cancer risk?
Women who have their first child under 30 years of age have a reduced overall lifetime risk of developing breast cancer. Women whose first full-term pregnancy occurs before the age of 20 have half the risk of breast cancer compared to those who never have children. Subsequent pregnancies increase protection against breast cancer.
The protective effect of pregnancy is not evident in women who have their first pregnancy between the ages of 30–34 years, and those who have their first pregnancy after 35 are at an increased risk compared to those who don’t have children.
Although having children at a younger age lowers the long-term risk, the first pregnancy at any age increases the short-term risk of breast cancer. Women who have recently given birth have a short-term increase in breast cancer risk which peaks around five years after childbirth and continues for an average of 24 years.
Q3. Does breastfeeding reduce the risk of breast cancer?
Breastfeeding lowers the risk of developing breast cancer. The longer you breastfeed, the more risk is reduced. Although mechanisms are not fully understood, breastfeeding changes breast tissue by eliminating cells with DNA damage and reduces the lifetime number of menstrual cycles, altering exposure to specific hormones which can influence breast cancer risk.
Q4. Does HRT cause breast cancer?
Whilst some forms of hormone replacement therapy, or HRT, are associated with an increase in breast cancer risk; the extent of the risk depends on the type of HRT and the duration of use.
With oestrogen-only HRT, there is little to no increased risk of breast cancer. This type of HRT is usually only recommended to people who have had their uterus removed (hysterectomy).
For combined HRT (oestrogen and progestogen), breast cancer risk increases when used over five years. Increased risk declines when the combined HRT treatment is stopped, but some risk remains if used for over ten years.
Q5. Is it true that I’m more at risk if I don’t have children?
Women who haven’t given birth have an increase risk of breast cancer compared to those who have given birth before the age of 30. However, those who give birth over the age of 35 have a higher risk than those who don’t have children. Having more children at a younger age reduces risk even more.
Q6. If I’m on a contraceptive pill or another type of hormonal contraception, am I at increased breast cancer risk?
The contraceptive pill contains both synthetic oestrogen and synthetic progesterone (known as progestogen) or progestogen-only. Studies have shown that taking combined oral contraceptives (oestrogen and progestogen) slightly increases breast cancer risk. The risk is no longer evident ten years after use has stopped.
Some studies suggest contraceptive pills containing progestogen-only may not be associated with breast cancer risk, while a more recent 2023 study has shown a very slight increase. More studies are needed to confirm this.
Other types of hormonal contraceptives include injections and hormone-releasing intrauterine systems (e.g., Mirena coil), which contain progestogen, and patches and vaginal rings, which use both oestrogen and progestogen. There are fewer studies into the risks associated with these types of contraceptives, although the risks are thought to be similar to those associated with the contraceptive pill.
Q7. Why are high levels of oestrogen potentially harmful?
Higher levels of circulating oestrogens are associated with an increased risk of breast cancer (this is also true for men). Oestrogen encourages certain cell types, including breast cells, to divide more often. The more a cell divides, the more likely mutations will accumulate, which may lead to breast cancer. Oestrogen also encourages the growth of oestrogen receptor-positive breast cancers.
For more details, see our biology of breast cancer review.
Q8. Do transgender women have an increased risk of breast cancer?
Several studies have shown transgender women (those assigned male sex at birth who identify as women) who undergo hormone treatment have an increased risk of breast cancer compared to cis men (who have not undergone treatment).
However, transgender women are still at a lower risk of breast cancer compared to cis women who have not undergone hormone treatment. Transgender women who take hormone therapy may have a higher risk of breast cancer than the cis male population but a lower risk than the cis female population.
For more information, see our transgender resource.
Q9. Do transgender men have an increased risk of breast cancer?
A Dutch study, based on a small sample size, found that transgender men (those assigned female sex at birth who identify as men) who undergo hormone treatment are at a lower risk of breast cancer compared to cis women (who have not undergone treatment) but at a higher risk than cis men.
Many transgender men undergo a double mastectomy (breast tissue removal), which reduces breast cancer risk. Nonetheless, everyone is susceptible to breast cancer, and not all trans men undergo mastectomies meaning they may remain at higher risk. Further studies are needed to assess the potential risks of long-term testosterone treatment.
For more information, see our transgender resource.
Q1. Are there any ethnic groups in the UK more at risk of breast cancer?
Some ethnic groups, including those with an Ashkenazi Jewish background, are more at risk than others. Some ethnic groups appear to have a lower risk. This may be due to genetics or lifestyle factors.
Individuals with an Ashkenazi Jewish background have a much higher risk of inheriting a BRCA gene mutation compared to other members of the UK population. Inheriting BRCA mutations increases breast cancer risk considerably. Please see Section 5 Q2 for more details about BRCA genes.
Studies have shown that some UK ethnic groups have lower breast cancer rates. Women from South Asian, Chinese, black Caribbean and black African ethnic groups have a lower incidence compared to white women. This is thought to be due to differences in known reproductive and lifestyle factors for the disease, such as having more children at a younger age; breastfeeding; lower body mass index post-menopause; lower alcohol consumption and less use of hormone replacement therapy.
Despite a lower breast cancer incidence compared to the white population, it is also true that black Caribbean, black African, Indian and Pakistani UK women are at greater risk of being diagnosed with breast cancer which is at a later stage, more aggressive and more difficult to treat. These differences are greater in older compared with younger women, and in black Carribean and African ethnic groups rather than South Asian ethnic groups. Compared to white women, black African women are much more likely to be diagnosed with oestrogen receptor negative (ER-) breast cancer, which is harder to treat than ER+ breast cancer. They are also more likely to be diagnosed with HER2+ breast cancer, which can also be difficult to treat.
Q2. Does a family history of breast cancer put someone at a higher risk?
Those who have inherited a specific gene mutation (e.g. a BRCA mutation) or with a strong family history of breast cancer (e.g. two first-degree relatives (mother, sister, or daughter) or one first-degree relative under 40 years who has had breast cancer) are at higher risk of getting the disease. Having one first-degree relative diagnosed with breast cancer increases your risk, and the risk is higher when you have a strong family history of the disease.
Having a BRCA mutation or a strong family history of breast cancer does not mean you will automatically get the disease; it means you are at higher risk. It should also be noted that most breast cancers occur in women who do not carry a single gene mutation or do not have a strong family history of the disease. Anyone can get breast cancer, although it is far more common in older women.
Q3. What are BRCA1 and BRCA2 genes?
BRCA1 and BRCA2 (BReast CAncer genes 1 and 2) are genes that produce proteins that help repair damaged DNA and help prevent cancer from developing.
Women and men carry two alleles (versions) of these genes. Those who inherit harmful variants (mutations) of either allele have an increased risk of several types of cancer, most notably breast and ovarian cancer in women and breast and prostate cancer in men. These mutations cause the protein to lose its function, so DNA repair is no longer functional. We call this loss of function mutations. Those with an inherited BRCA mutation also tend to develop cancer at a younger age. BRCA mutations can be inherited from either parent, and each child of a parent carrying a BRCA mutation has a 1 in 2 chance of inheriting the mutation.
Q4. Is there a connection between breast cancer and ovarian cancer and are the causes the same?
There is occasionally a strong connection between breast and ovarian cancer when either is due to a single inherited gene mutation, such as a mutation in a BRCA gene. This is known as “hereditary breast and ovarian cancer syndrome”. If either cancer is hereditary, then your risk is significantly increased for both cancers.
If your cancer is not hereditary (e.g., not due to a single inherited mutation), then there is a loose connection based on both cancers sharing several common risk factors.
Q5. Why are taller women at a higher risk of getting breast cancer?
A study that included 5 million women found that being tall is a risk factor for hormone-responsive breast cancer. The reasons for this are not well understood, although it’s likely that genetic factors and biological pathways which affect adult height may explain the association. For example, taller women have higher levels of insulin-like growth factor-1 (IGF-1), which also promotes cell division and inhibits programmed cell death (increasing cancer risk). Cancer incidence increases with increasing adult height for most types of cancers.
Q1. Does having larger breasts increase the risk of breast cancer?
The research behind this question is inconclusive. Some early studies identified a link between having large breasts and increased breast cancer risk, but recent studies suggest an increased breast size does not appear to increase the risk of breast cancer.
What is more important is your breast density (i.e. how much fat tissue compared to fibrous and glandular tissue is in your breasts, which is detected by a mammogram). Moreover, the definition of a large breast in terms of size has not yet been clarified.
Q2. Am I more at risk of breast cancer if I have breast implants?
There is no convincing scientific evidence to show implants increase breast cancer risk. However, breast implants may make breast cancer harder to detect.
There is also no evidence that breast reconstruction after cancer treatment carries an increased risk of breast cancer recurrence, whether or not implants are involved. Certain types of “textured” breast implants (no longer available in the EU or UK) slightly increase the risk of a rare type of lymphoma.
Q3. Is stress a risk factor for breast cancer?
So far, there is limited evidence of a direct link between stress and breast cancer risk, with much of the research producing conflicting results.
Some studies have shown stress/psychological factors to increase breast cancer risk. Meanwhile, others have shown no association. However, it can be more difficult for people to keep healthy during stressful periods, so stress may indirectly increase the risk of cancer. Although again, research on this is limited.
Q4. What does it mean to have dense breasts – is this a risk?
High breast (or mammographic) density is a significant risk factor for breast cancer. Breasts are described as “dense” if they have lots of fibrous or glandular tissue and not much fat tissue. The density of breast tissue can only be detected on a mammogram and is not related to the size of your breasts or how they feel. Breasts are naturally more or less dense (due partly to inheritance), although breast density changes over time, and breasts tend to become less dense with age.
Exposure to some EDCs (e.g., BPA) may increase breast density, especially if exposure occurs in the womb or during puberty. Dense breasts also make mammograms more difficult to interpret.
Q5. Does fluoride in drinking water increase breast cancer risk?
There is insufficient evidence to conclude that fluoride in drinking water increases breast cancer risk. Fluoride is a substance added to drinking water to prevent tooth decay.
Q6. Does chlorine in drinking water increase breast cancer risk?
There is insufficient evidence to conclude that chlorine in drinking water increases breast cancer risk, although some studies claim it could. Chlorine is added to water as a disinfectant.
Q7. Can mammograms increase the risk of breast cancer?
Mammograms deliver very low levels of ionising radiation, which will slightly increase breast cancer risk.
According to Public Health England (2017), if a woman attends all seven screening examinations between the age of 50 up to her 71st birthday, the risk of radiation-induced cancer is between 1 in 7,000 to 1 in 14,000.
They also estimate that about 400 to 800 cancers are detected by the NHS mammography screening programme for every cancer-induced, and the mortality benefit of screening exceeds the radiation-induced detriment by about 150:1 to 300:1.
Q8. Does socioeconomic status affect your risk of breast cancer?
Women who live in areas of higher socioeconomic status have an increased risk of breast cancer compared to those who live in more disadvantaged areas.
The reasons may be associated with reproductive and hormonal factors, such as later age at first childbirth, having fewer children and less breastfeeding, and certain lifestyle factors.
Q9. Does where you live affect your risk of breast cancer?
Women who live in wealthier countries have an increased risk of breast cancer compared to those who live in poorer countries. The reasons may be associated with reproductive factors, such as earlier age at menarche (first period), later age at first childbirth, having fewer children, less breastfeeding, and lifestyle factors such as increased obesity, alcohol consumption, and reduced physical activity.
Living in urban areas, as opposed to rural areas, is also associated with increased risk. The reasons for this may be due to environmental factors such as increased pollution levels in urban areas or reproductive and lifestyle factors.
Q10. Do underwire bras increase my risk of breast cancer?
Underwire bras do not increase your risk of breast cancer.
The claim is based on a suggestion that underwire bras block the drainage of lymph fluid from the bottom of the breast so it can’t get back into your body, but there is no reliable scientific evidence to support this claim.
Q11. Does night shift work increase breast cancer risk?
It is unclear whether night shift work may increase breast cancer risk.
In 2019, the International Agency for Research on Cancer (IARC) classified night shift work as “probably carcinogenic to humans” and stated there was limited evidence that night shift work causes breast cancer. Since 2019, numerous epidemiological studies and meta-studies have been published on this subject, including a re-evaluation of the research by the IARC in 2020 which reached the same conclusion.
One recent study of Norwegian Offshore Petroleum Workers found night shift work may increase breast cancer risk in men. However, the Generations Study, which has looked at the data relating to over 100,000 UK women has shown no overall association between breast cancer risk and overnight working.
A suggested reason for any potential increase in breast cancer risk in night-shift workers is that they have lower levels of the hormone melatonin, which plays a central role in regulating the body’s sleep cycle or circadian rhythm. Melatonin production peaks at night and is lower during the day. Light at night inhibits the release of this hormone into the bloodstream. Melatonin is known to be protective against breast cancer. It reduces the multiplication and spread of breast cancer cells and breast cancer stem cells (where cancers often originate), and it is anti-oestrogenic.
Q12. Does mobile phone use increase breast cancer risk?
Studies looking at mobile phone use over long periods of time have shown no evidence of an increased breast cancer risk. Additionally, there is no convincing evidence that storing mobile phones in bras increases breast cancer risk, as only a few very small studies have looked into this.
Research is still ongoing to ensure effects on cancer risk in the long-term, but none have been identified so far.
Q13. Does having type 2 diabetes increase breast cancer risk?
Breast cancer incidence has previously been shown to be higher in women who have type 2 diabetes compared to those who don’t. This is also particularly true for postmenopausal women. The reasons behind this increase are still not completely understood. Still, scientists believe there could be both direct (e.g., specific changes to the body in people with type 2 diabetes may be affecting risk) and indirect (e.g., being overweight, which is a risk factor for both diseases) causes.
About breast cancer
Q1. What is breast cancer?
American Cancer Society. What Is Breast Cancer? [Internet]. [cited 2023 Jul 21]. Available from: https://www.cancer.org/cancer/types/breast-cancer/about/what-is-breast-cancer.html
Breast Cancer UK. The Biology of Breast Cancer [Internet]. 2016 [cited 2023 Jul 20]. Available from: https://cdn.breastcanceruk.org.uk/uploads/2019/07/Background_Briefing_Biology_of_Breast_Cancer_31_05_16_FINAL_nw.pdf
Q2. How common is breast cancer?
Cancer Research UK. Breast cancer statistics [Internet]. [cited 2023 Jul 20]. Available from: https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer
World Health Organisation. Breast cancer now most common form of cancer: WHO taking action [Internet]. 2021 [cited 2023 Jul 20]. Available from: https://www.who.int/news/item/03-02-2021-breast-cancer-now-most-common-form-of-cancer-who-taking-action
Q3. What are the most common types of breast cancer?
Cancer Research UK. Breast cancer in men [Internet]. [cited 2023 Jul 20]. Available from: https://www.cancerresearchuk.org/about-cancer/breast-cancer/types/male-breast-cancer
Cancer research UK. Tests on your breast cancer cells [Internet]. [cited 2023 Jul 20]. Available from: https://www.cancerresearchuk.org/about-cancer/breast-cancer/getting-diagnosed/tests-breast-cancer-cells
Cancer Research UK. Types of breast cancer and related breast conditions [Internet]. [cited 2023 Jul 20]. Available from: https://www.cancerresearchuk.org/about-cancer/breast-cancer/types
Cardoso F, Bartlett JMS, Slaets L, van Deurzen CHM, van Leeuwen-Stok E, Porter P, et al. Characterization of male breast cancer: results of the EORTC 10085/TBCRC/BIG/NABCG International Male Breast Cancer Program. Annals of Oncology. 2018 Feb 1;29(2):405–17. Available from: https://www.sciencedirect.com/science/article/pii/S09237534 19350379
Q4. What are the symptoms of breast cancer?
Cancer Research UK. Symptoms of breast cancer [Internet]. [cited 2023 Jul 20]. Available from: https://www.cancerresearchuk.org/about-cancer/breast-cancer/symptoms
Q5. What should I do if I think I have breast cancer?
NHS. Breast cancer in women – Diagnosis [Internet]. [cited 2023 Jul 20]. Available from: https://www.nhs.uk/conditions/breast-cancer/diagnosis/
Q6. How is breast cancer diagnosed?
NHS. Biopsy overview [Internet]. [cited 2023 Jul 21]. Available from: https://www.nhs.uk/conditions/biopsy/
NHS. New imaging technology improving breast cancer diagnosis [Internet]. 2023 [cited 2023 Jul 21]. Available from: https://www.ncic.nhs.uk/news/new-imaging-technology-improving-breast-cancer-diagnosis
NICE. Contrast-enhanced spectral mammography for breast cancer Medtech innovation briefing [Internet]. NICE Guidance. 2022 [cited 2023 Jul 20]. Available from: www.nice.org.uk/guidance/mib304
Q7. What are the causes of breast cancer?
Breast Cancer UK. Breast Cancer Risk Factors. 2019 [cited 2023 Jul 21]; Available from: https://cdn.breastcanceruk.org.uk/uploads/2019/08/BCUK_Breast_cancer_risk_factors_brief_v1._12.6.2019.pdf
Lifestyle risk factors
Q1. Is being overweight a breast cancer risk?
Cancer Australia. Risk factors for breast cancer: A review of the evidence. Surry Hills, NSW; 2018. Available from: https://www.canceraustralia.gov.au/publications-and-resources/cancer-australia-publications/risk-factors-breast-cancer-review-evidence-2018
Q2. Does being overweight or obese increase the risk of breast cancer in premenopausal women?
Darbre PD. Endocrine Disruptors and Obesity. Curr Obes Rep [Internet]. 2017 [cited 2023 Jul 21];6(1):18–27. Available from: https://pubmed.ncbi.nlm.nih.gov/28205155/
García-Estévez L, Cortés J, Pérez S, Calvo I, Gallegos I, Moreno-Bueno G. Obesity and Breast Cancer: A Paradoxical and Controversial Relationship Influenced by Menopausal Status. Front Oncol. 2021. 11:705911. https://doi.org/10.3389/fonc.2021.705911
Schoemaker MJ, Nichols HB, Wright LB, Brook MN, Jones ME, O’Brien KM, et al. Adult weight change and premenopausal breast cancer risk: A prospective pooled analysis of data from 628,463 women. Int J Cancer [Internet]. 2020 [cited 2023 Jul 21];147(5):1306–14. Available from: https://pubmed.ncbi.nlm.nih.gov/32012248/
Torres-De La Roche LA, Steljes I, Janni W, Friedl TWP, De Wilde RL. The Association between Obesity and Premenopausal Breast Cancer According to Intrinsic Subtypes – a Systematic Review. Geburtshilfe Frauenheilkd [Internet]. 2020 [cited 2023 Jul 21];80(6):601. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7299685/
van den Brandt PA, Ziegler RG, Wang M, Hou T, Li R, Adami HO, et al. Body size and weight change over adulthood and risk of breast cancer by menopausal and hormone receptor status: a pooled analysis of 20 prospective cohort studies. Eur J Epidemiol [Internet]. 2021 [cited 2023 Jul 21];36(1):37–55. Available from: https://pubmed.ncbi.nlm.nih.gov/33128203/
Q3. Is there a link between eating processed meat and breast cancer?
Anderson JJ, Darwis NDM, Mackay DF, Celis-Morales CA, Lyall DM, Sattar N, et al. Red and processed meat consumption and breast cancer: UK Biobank cohort study and meta-analysis. European journal of cancer [Internet]. 2018 [cited 2023 Jul 21];90:73–82. Available from: https://pubmed.ncbi.nlm.nih.gov/29274927/
Diallo A, Deschasaux M, Latino-Martel P, Hercberg S, Galan P, Fassier P, et al. Red and processed meat intake and cancer risk: Results from the prospective NutriNet-Santé cohort study. Int J Cancer [Internet]. 2018 [cited 2023 Jul 21];142(2):230–7. Available from: https://pubmed.ncbi.nlm.nih.gov/28913916/
Farvid MS, Stern MC, Norat T, Sasazuki S, Vineis P, Weijenberg MP, et al. Consumption of red and processed meat and breast cancer incidence: A systematic review and meta-analysis of prospective studies. Int J Cancer [Internet]. 2018 [cited 2023 Jul 21];143(11):2787–99. Available from: https://pubmed.ncbi.nlm.nih.gov/30183083/
Farvid MS, Sidahmed E, Spence ND, Mante Angua K, Rosner BA, Barnett JB. Consumption of red meat and processed meat and cancer incidence: a systematic review and meta-analysis of prospective studies. Eur J Epidemiol [Internet]. 2021 [cited 2023 Jul 21];36(9):937–51. Available from: https://pubmed.ncbi.nlm.nih.gov/34455534/
Q4. Can a healthy diet help to prevent breast cancer?
AICR, WCRF. Diet, nutrition, physical activity and breast cancer: a global perspective. Continuous Update Project Report. 2018. https://www.wcrf.org/wp-content/uploads/2021/02/Breast-cancer-report.pdf
Atoum M, Alzoughool F. Vitamin D and Breast Cancer: Latest Evidence and Future Steps. Breast Cancer (Auckl) [Internet]. 2017 Dec 19 [cited 2023 Jul 21];11. Available from: https://pubmed.ncbi.nlm.nih.gov/29434472/
British Nutrition Foundation. Fibre [Internet]. [cited 2023 Jul 21]. Available from: https://www.nutrition.org.uk/healthy-sustainable-diets/starchy-foods-sugar-and-fibre/fibre/
Farvid MS, Spence ND, Holmes MD, Barnett JB. Fiber consumption and breast cancer incidence: A systematic review and meta-analysis of prospective studies. Cancer [Internet]. 2020 Jul 1 [cited 2023 Jul 21];126(13):3061–75. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/cncr.32816
Q5. Does drinking alcohol increase my breast cancer risk?
AICR, WCRF. Diet, nutrition, physical activity and breast cancer: a global perspective. Continuous Update Project Report. 2018. https://www.wcrf.org/wp-content/uploads/2021/02/Breast-cancer-report.pdf
Freudenheim JL. Alcohol’s Effects on Breast Cancer in Women. Alcohol Res. 2020 Jun 18;40(2):11. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC7295577/
Q6. What is the ideal diet to decrease my risk of breast cancer?
AICR, WCRF. Diet, nutrition, physical activity and breast cancer: a global perspective. Continuous Update Project Report. 2018. https://www.wcrf.org/wp-content/uploads/2021/02/Breast-cancer-report.pdf
Xiao Y, Xia J, Li L, Ke Y, Cheng J, Xie Y, et al. Associations between dietary patterns and the risk of breast cancer: A systematic review and meta-analysis of observational studies. Breast Cancer Research [Internet]. 2019 Jan 29 [cited 2023 Jul 21];21(1):1–22. Available from: https://breast-cancer-research.biomedcentral.com/articles/10.1186/s13058-019-1096-1
Q7. Does eating a vegan or vegetarian diet decrease breast cancer risk?
AICR, WCRF. Diet, nutrition, physical activity and breast cancer: a global perspective. Continuous Update Project Report. 2018. https://www.wcrf.org/wp-content/uploads/2021/02/Breast-cancer-report.pdf
Gathani T, Barnes I, Ali R, Arumugham R, Chacko R, Digumarti R, et al. Lifelong vegetarianism and breast cancer risk: A large multicentre case control study in India. BMC Womens Health [Internet]. 2017 Jan 18 [cited 2023 Jul 21];17(1):1–6. Available from: https://bmcwomenshealth.biomedcentral.com/articles/10.1186/s12905-016-0357-8
Rigi S, Mousavi SM, Benisi-Kohansal S, Azadbakht L, Esmaillzadeh A. The association between plant-based dietary patterns and risk of breast cancer: a case–control study. Scientific Reports 2021 11:1 [Internet]. 2021 Feb 9 [cited 2023 Jul 21];11(1):1–10. Available from: https://www.nature.com/articles/s41598-021-82659-6
Romanos-Nanclares A, Willett WC, Rosner BA, Collins LC, Hu FB, Toledo E, et al. Healthful and unhealthful plant-based diets and risk of breast cancer in U.S. women: Results from the nurses’ health studies. Cancer Epidemiology Biomarkers and Prevention [Internet]. 2021 Oct 1 [cited 2023 Jul 21];30(10):1921–31. Available from: https://dx.doi.org/10.1158/1055-9965.EPI-21-0352
World Cancer Research Fund. Healthy Living. 2023 [cited 2023 Jul 21]. Are plant-based meat alternatives better for us? Available from: https://www.wcrf-uk.org/our-blog/are-plant-based-meat-alternatives-better-for-us/
Q8. Does eating organic food decrease my risk of getting breast cancer?
Bradbury KE, Balkwill A, Spencer EA, Roddam AW, Reeves GK, Green J, et al. Organic food consumption and the incidence of cancer in a large prospective study of women in the United Kingdom. Br J Cancer [Internet]. 2014 Mar 27 [cited 2023 Jul 21];110(9):2321–6. Available from: https://www.nature.com/articles/bjc2014148
Park YMM, White A, Niehoff N, O’Brien K, Sandler D. Association Between Organic Food Consumption and Breast Cancer Risk: Findings from the Sister Study (P18-038-19). Curr Dev Nutr. 2019 Jun 1;3:nzz039.P1818-038-19. https://doi.org/10.1093/cdn/nzz039.P18-038-19
Rebouillat P, Vidal R, Cravedi JP, Taupier-Letage B, Debrauwer L, Gamet-Payrastre L, et al. Prospective association between dietary pesticide exposure profiles and postmenopausal breast-cancer risk in the NutriNet-Santé cohort. Int J Epidemiol [Internet]. 2021 Aug 1 [cited 2023 Jul 21];50(4):1184–98. Available from: https://pubmed.ncbi.nlm.nih.gov/33720364/
Stur E, Aristizabal-Pachon AF, Peronni KC, Agostini LP, Waigel S, Chariker J, et al. Glyphosate-based herbicides at low doses affect canonical pathways in estrogen positive and negative breast cancer cell lines. PLoS One [Internet]. 2019 Jul 1 [cited 2023 Jul 21];14(7):e0219610. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0219610
Yang KJ, Lee J, Park HL. Organophosphate Pesticide Exposure and Breast Cancer Risk: A Rapid Review of Human, Animal, and Cell-Based Studies. Int J Environ Res Public Health [Internet]. 2020 Jul 13 [cited 2023 Jul 21];17(14):5030. Available from: https://www.mdpi.com/1660-4601/17/14/5030/htm
Q9. Does drinking cow’s milk increase breast cancer risk?
Chen L, Li M, Li H. Milk and yogurt intake and breast cancer risk A meta-analysis. Medicine [Internet]. 2019 [cited 2023 Jul 21];98(12):e14900. Available from: http://dx.doi.org/10.1097/MD.0000000000014900
He Y, Tao Q, Zhou F, Si Y, Fu R, Xu B, et al. The relationship between dairy products intake and breast cancer incidence: a meta-analysis of observational studies. BMC Cancer [Internet]. 2021 Oct 15 [cited 2023 Jul 21];21(1):1–12. Available from: https://bmccancer.biomedcentral.com/articles/10.1186/s12885-021-08854-w
Jeyaraman MM, Abou-Setta AM, Grant L, Farshidfar F, Copstein L, Lys J, et al. Dairy product consumption and development of cancer: an overview of reviews. BMJ Open [Internet]. 2019 Jan 1 [cited 2023 Jul 21];9(1):e023625. Available from: https://bmjopen.bmj.com/content/9/1/e023625
He Y, Tao Q, Zhou F, Si Y, Fu R, Xu B, et al. Diet, insulin-like growth factor-1 and cancer risk. Proceedings of the Nutrition Society [Internet]. 2011 [cited 2023 Jul 21];70(3):385–8. Available from: https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/diet-insulinlike-growth-factor1-and-cancer-risk/DB006BA4B70E896E51DA23BA96A740BB
Wu Y, Huang R, Wang M, Bernstein L, Bethea TN, Chen C, et al. Dairy foods, calcium, and risk of breast cancer overall and for subtypes defined by estrogen receptor status: a pooled analysis of 21 cohort studies. Am J Clin Nutr. 2021 Aug 1;114(2):450–61. https://www.sciencedirect.com/science/article/pii/S0002916522003616?via%3Dihub
Zang J, Shen M, Du S, Chen T, Zou S. The Association between Dairy Intake and Breast Cancer in Western and Asian Populations: A Systematic Review and Meta-Analysis. J Breast Cancer [Internet]. 2015 Dec 1 [cited 2023 Jul 21];18(4):313–22. Available from: https://pubmed.ncbi.nlm.nih.gov/26770237/
Q10. Can vitamin D supplements reduce my breast cancer risk?
Atoum M, Alzoughool F. Vitamin D and Breast Cancer: Latest Evidence and Future Steps. Breast Cancer (Auckl) [Internet]. 2017 Dec 19 [cited 2023 Jul 21];11. Available from: https://pubmed.ncbi.nlm.nih.gov/29434472/
Atoum, M., & Alzoughool, F. (2017). Vitamin D and Breast Cancer: Latest Evidence and Future Steps. Breast cancer : basic and clinical research, 11, 1178223417749816. https://doi.org/10.1177/1178223417749816
Li Z, Wu L, Zhang J, Huang X, Thabane L, Li G. Effect of Vitamin D Supplementation on Risk of Breast Cancer: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Front Nutr. 2021 Apr 1;8:655727. https://www.frontiersin.org/articles/10.3389/fnut.2021.655727/full
Q11. Does consuming too much sugar increase breast cancer risk?
AICR, WCRF. Diet, nutrition, physical activity and breast cancer: a global perspective. Continuous Update Project Report. 2018. https://www.wcrf.org/wp-content/uploads/2021/02/Breast-cancer-report.pdf
Debras C, Chazelas E, Srour B, Kesse-Guyot E, Julia C, Zelek L, et al. Total and added sugar intakes, sugar types, and cancer risk: results from the prospective NutriNet-Santé cohort. Am J Clin Nutr. 2020 Nov 1;112(5):1267–79. https://doi.org/10.1093/ajcn/nqaa246
Lu S, Qian Y, Huang X, Yu H, Yang J, Han R, et al. The association of dietary pattern and breast cancer in Jiangsu, China: A population-based case-control study. PLoS One [Internet]. 2017 Sep 1 [cited 2023 Jul 21];12(9):e0184453. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0184453
Q12. Does eating products containing artificial sweeteners increase breast cancer risk?
Debras C, Chazelas E, Srour B, Druesne-Pecollo N, Esseddik Y, de Edelenyi FS, et al. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study. PLoS Med [Internet]. 2022 Mar 1 [cited 2023 Jul 21];19(3):e1003950. Available from: https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003950
Riboli E, Beland FA, Lachenmeier DW, Marques MM, Phillips DH, Schernhammer E, et al. Carcinogenicity of aspartame, methyleugenol, and isoeugenol. Lancet Oncol [Internet]. 2023 Jul [cited 2023 Jul 21];0(0). Available from: http://www.thelancet.com/article/S1470204523003418/fulltext
Q13. Can eating soy products increase breast cancer risk?
Boutas I, Kontogeorgi A, Dimitrakakis C, Kalantaridou SN. Soy Isoflavones and Breast Cancer Risk: A Meta-analysis. In Vivo [Internet]. 2022 Mar 1 [cited 2023 Jul 21];36(2):556–62. Available from: https://pubmed.ncbi.nlm.nih.gov/35241506/
Kazemi A, Barati-Boldaji R, Soltani S, Mohammadipoor N, Esmaeilinezhad Z, Clark CCT, et al. Intake of Various Food Groups and Risk of Breast Cancer: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies. Advances in Nutrition. 2021 May 1;12(3):809–49. https://doi.org/10.1093/advances/nmaa147
Messina M, Mejia SB, Cassidy A, Duncan A, Kurzer M, Nagato C, et al. Neither soyfoods nor isoflavones warrant classification as endocrine disruptors: a technical review of the observational and clinical data. Crit Rev Food Sci Nutr [Internet]. 2022 [cited 2023 Jul 21];62(21):5824–85. Available from: https://pubmed.ncbi.nlm.nih.gov/33775173/
Wei Y, Lv J, Guo Y, Bian Z, Gao M, Du H, et al. Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose–response meta-analysis. Eur J Epidemiol [Internet]. 2020 Jun 1 [cited 2023 Jul 21];35(6):567–78. Available from: https://link.springer.com/article/10.1007/s10654-019-00585-4
Q14. Does physical activity affect my risk of breast cancer?
Cannioto RA, Hutson A, Dighe S, McCann W, McCann SE, Zirpoli GR, et al. Physical Activity Before, During, and After Chemotherapy for High-Risk Breast Cancer: Relationships With Survival. JNCI: Journal of the National Cancer Institute [Internet]. 2021 Jan 4 [cited 2023 Jul 21];113(1):54–63. Available from: https://dx.doi.org/10.1093/jnci/djaa046
Gonçalves AK, Dantas Florêncio GL, Maissonnete De Atayde Silva MJ, Cobucci RN, Giraldo PC, Cote NM. Effects of physical activity on breast cancer prevention: a systematic review. J Phys Act Health [Internet]. 2014 [cited 2023 Aug 4];11(2):445–54. Available from: https://pubmed.ncbi.nlm.nih.gov/23416687/
Guo W, Fensom GK, Reeves GK, Key TJ. Physical activity and breast cancer risk: results from the UK Biobank prospective cohort. British Journal of Cancer 2020 122:5 [Internet]. 2020 Jan 10 [cited 2023 Aug 4];122(5):726–32. Available from: https://www.nature.com/articles/s41416-019-0700-6
Spei ME, Samoli E, Bravi F, La Vecchia C, Bamia C, Benetou V. Physical activity in breast cancer survivors: A systematic review and meta-analysis on overall and breast cancer survival. Breast [Internet]. 2019 Apr 1 [cited 2023 Aug 4];44:144–52. Available from: http://www.thebreastonline.com/article/S0960977619300207/fulltext
Xu Y, Rogers CJ. Physical Activity and Breast Cancer Prevention: Possible Role of Immune Mediators. Front Nutr. 2020 Oct 8;7:557997. https://www.frontiersin.org/articles/10.3389/fnut.2020.557997/full
Q15. Does smoking increase breast cancer risk?
Jones ME, Schoemaker MJ, Wright LB, Ashworth A, Swerdlow AJ. Smoking and risk of breast cancer in the Generations Study cohort. Breast Cancer Res [Internet]. 2017 Nov 22 [cited 2023 Jul 21];19(1). Available from: https://pubmed.ncbi.nlm.nih.gov/29162146/
Park HA, Neumeyer S, Michailidou K, Bolla MK, Wang Q, Dennis J, et al. Mendelian randomisation study of smoking exposure in relation to breast cancer risk. Br J Cancer [Internet]. 2021 Oct 12 [cited 2023 Jul 21];125(8):1135–45. Available from: https://pubmed.ncbi.nlm.nih.gov/34341517/
van den Brandt PA. A possible dual effect of cigarette smoking on the risk of postmenopausal breast cancer. Eur J Epidemiol [Internet]. 2017 Aug 1 [cited 2023 Jul 21];32(8):683–90. Available from: https://pubmed.ncbi.nlm.nih.gov/28710542/
Q16. Does vaping increase breast cancer risk?
Cancer Research UK. Is vaping harmful? [Internet]. [cited 2023 Jul 21]. Available from: https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/smoking-and-cancer/is-vaping-harmful
National Academies of Sciences Engineering and Medicine, Health and Medicine Division, Board on Population Health and Public Health Practice, Committee on the Review of the Health Effects of Electronic Systems Nicotine Delivery. Toxicology of E-Cigarette Constituents. In: Eaton DL, Kwan LY, Stratton K, editors. Public Health Consequences of E-Cigarettes [Internet]. Washington: National Academies Press (US); 2018 [cited 2023 Jul 21]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507171/
Chemicals and the environment
Q1. How might exposure to certain chemicals increase breast cancer risk?
Travis RC, Key TJ. Oestrogen exposure and breast cancer risk. Breast Cancer Res [Internet]. 2003 [cited 2023 Jul 21];5(5):239. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC314432/
WHO, UNEP. State of the Science of Endocrine Disrupting Chemicals [Internet]. 2012 [cited 2023 Jul 21]. Available from: https://www.unep.org/resources/report/state-science-endocrine-disrupting-chemicals
Q2. Where are endocrine-disrupting chemicals found?
Breast Cancer UK. Endocrine disrupting chemicals [Internet]. 2018 [cited 2023 Jul 21]. Available from: https://cdn.breastcanceruk.org.uk/uploads/2019/08/BCUK_EDC_brief_v2_20.9.18.pdf
Endocrine Society. Common EDCs and Where They Are Found [Internet]. [cited 2023 Jul 21]. Available from: https://www.endocrine.org/topics/edc/what-edcs-are/common-edcs
Q3. Why don’t other cancer charities highlight exposures to harmful chemicals as cancer risk factors?
United Nations Environment Programme. Global Chemicals Outlook II: From Legacies to Innovative Solutions Programme [Internet]. 2019 [cited 2023 Jul 21]. Available from: https://www.unep.org/resources/report/global-chemicals-outlook-ii-legacies-innovative-solutions
WHO, UNEP. State of the Science of Endocrine Disrupting Chemicals [Internet]. 2012 [cited 2023 Jul 21]. Available from: https://www.unep.org/resources/report/state-science-endocrine-disrupting-chemicals
Q4. Does drinking water from plastic bottles increase breast cancer risk?
Le HH, Carlson EM, Chua JP, Belcher SM. Bisphenol A is released from polycarbonate drinking bottles and mimics the neurotoxic actions of estrogen in developing cerebellar neurons. Toxicol Lett [Internet]. 2008 Jan 1 [cited 2023 Jul 21];176(2):149. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2254523/
Sax L. Polyethylene terephthalate may yield endocrine disruptors. Environ Health Perspect [Internet]. 2010 Apr [cited 2023 Jul 21];118(4):445–8. Available from: https://pubmed.ncbi.nlm.nih.gov/20368129/
Q5. Do antiperspirants and deodorants increase breast cancer risk?
Breast Cancer UK. Aluminium salts as antiperspirants [Internet]. 2019 [cited 2023 Jul 21]. Available from: https://cdn.breastcanceruk.org.uk/uploads/2019/09/short-brief-aluminium-salts-as-antiperspirants-13.9.19.pdf
Darbre PD. Endocrine disrupting chemicals and breast cancer cells. Advances in pharmacology [Internet]. 2021 Jan 1 [cited 2023 Jul 21];92:485–520. Available from: https://pubmed.ncbi.nlm.nih.gov/34452695/
Q6. Does using products containing lavender oil increase my risk of breast cancer?
Endocrine Society. Chemicals in lavender and tea tree oil appear to be hormone disruptors | [Internet]. 2018 [cited 2023 Jul 21]. Available from: https://www.endocrine.org/news-and-advocacy/news-room/2018/chemicals-in-lavender-and-tea-tree-oil-appear-to-be-hormone-disruptors
Hawkins J, Hires C, Dunne E, Keenan L. Prevalence of endocrine disorders among children exposed to Lavender Essential Oil and Tea Tree Essential Oils. Int J Pediatr Adolesc Med. 2022 Jun 1;9(2):117–24. https://www.sciencedirect.com/science/article/pii/S2352646721000855?via%3Dihub
Ramsey JT, Li Y, Arao Y, Naidu A, Coons LA, DIaz A, et al. Lavender Products Associated With Premature Thelarche and Prepubertal Gynecomastia: Case Reports and Endocrine-Disrupting Chemical Activities. J Clin Endocrinol Metab [Internet]. 2019 Nov 1 [cited 2023 Jul 21];104(11):5393–405. Available from: https://dx.doi.org/10.1210/jc.2018-01880
Q7. How can I tell if personal care products contain Endocrine Disrupting Chemicals (EDCs)?
See the links in question.
Q8. What sunscreens should I avoid?
Barr L, Alamer M, Darbre PD. Measurement of concentrations of four chemical ultraviolet filters in human breast tissue at serial locations across the breast. Journal of Applied Toxicology [Internet]. 2018 Aug 1 [cited 2023 Jul 21];38(8):1112–20. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/jat.3621
Majhi PD, Sharma A, Roberts AL, Daniele E, Majewski AR, Chuong LM, et al. Effects of Benzophenone-3 and Propylparaben on Estrogen Receptor–Dependent R-Loops and DNA Damage in Breast Epithelial Cells and Mice. Environ Health Perspect [Internet]. 2020 Jan 1 [cited 2023 Jul 21];128(1). Available from: https://ehp.niehs.nih.gov/doi/10.1289/EHP5221
EcoWatch. Your Sunscreen Is Toxic: How To Find One That’s Safe for You & the Planet [Internet]. 2022 [cited 2023 Jul 21]. Available from: https://www.ecowatch.com/sunscreen-guide.html
Q9. Does eating food stored in plastic containers or takeaway boxes increase breast cancer risk?
EFSA. Scientific Opinion on the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs. EFSA Journal [Internet]. 2015 Jan 1 [cited 2023 Jul 21];13(1). Available from: https://www.efsa.europa.eu/en/efsajournal/pub/3978
Mercea P. Physicochemical processes involved in migration of bisphenol A from polycarbonate. J Appl Polym Sci [Internet]. 2009 Apr 15 [cited 2023 Jul 21];112(2):579–93. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/app.29421
Muncke J, Andersson AM, Backhaus T, Boucher JM, Carney Almroth B, Castillo Castillo A, et al. Impacts of food contact chemicals on human health: a consensus statement. Environmental Health [Internet]. 2020 Mar 3 [cited 2023 Jul 21];19(1):1–12. Available from: https://ehjournal.biomedcentral.com/articles/10.1186/s12940-020-0572-5
Stillwater BJ, Bull AC, Romagnolo DF, Neumayer LA, Donovan MG, Selmin OI. Bisphenols and Risk of Breast Cancer: A Narrative Review of the Impact of Diet and Bioactive Food Components. Front Nutr. 2020 Nov 19;7:581388. https://www.frontiersin.org/articles/10.3389/fnut.2020.581388/full
Q10. Can my child be exposed to EDCs in the womb?
Vandenberg LN, Maffini M V., Schaeberle CM, Ucci AA, Sonnenschein C, Rubin BS, et al. Perinatal exposure to the xenoestrogen bisphenol-A induces mammary intraductal hyperplasias in adult CD-1 mice. Reproductive Toxicology. 2008 Nov 1;26(3–4):210–9. https://www.sciencedirect.com/science/article/abs/pii/S0890623808002451?via%3Dihub
Wormsbaecher C, Hindman AR, Avendano A, Cortes-Medina M, Jones CE, Bushman A, et al. In utero estrogenic endocrine disruption alters the stroma to increase extracellular matrix density and mammary gland stiffness. Breast Cancer Research [Internet]. 2020 May 5 [cited 2023 Jul 21];22(1):1–12. Available from: https://breast-cancer-research.biomedcentral.com/articles/10.1186/s13058-020-01275-w
Q11. Does exposure to parabens affect breast cancer risk?
Hager E, Chen J, Zhao L. Minireview: Parabens Exposure and Breast Cancer. Int J Environ Res Public Health [Internet]. 2022 Feb 1 [cited 2023 Jul 21];19(3). Available from: https://pubmed.ncbi.nlm.nih.gov/35162895/
Mogus JP, Laplante CD, Bansal R, Matouskova K, Schneider BR, Daniele E, et al. Exposure to Propylparaben During Pregnancy and Lactation Induces Long-Term Alterations to the Mammary Gland in Mice. Endocrinology [Internet]. 2021 Jun 1 [cited 2023 Jul 21];162(6). Available from: https://pubmed.ncbi.nlm.nih.gov/33724348/
Q12. What are microplastics, and can they affect breast cancer risk?
Britannica. Microplastics [Internet]. 2022 [cited 2023 Jul 21]. Available from: https://www.britannica.com/technology/microplastic
Leslie HA, van Velzen MJM, Brandsma SH, Vethaak AD, Garcia-Vallejo JJ, Lamoree MH. Discovery and quantification of plastic particle pollution in human blood. Environ Int. 2022 May 1;163:107199. https://www.sciencedirect.com/science/article/pii/S0160412022001258
Munoz-Pineiro MA. MICROPLASTICS: Focus on Food and Health. Publications Office of the European Union [Internet]. 2018 [cited 2023 Jul 21];123–52. Available from: https://publications.jrc.ec.europa.eu/repository/handle/JRC110629
Ragusa A, Notarstefano V, Svelato A, Belloni A, Gioacchini G, Blondeel C, et al. Raman Microspectroscopy Detection and Characterisation of Microplastics in Human Breastmilk. Polymers (Basel) [Internet]. 2022 Jul 1 [cited 2023 Jul 21];14(13). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9269371/
Q13. What are forever chemicals?
CHEMTrust. PFAS – the ’Forever Chemicals [Internet]. Vol. 126. Public Health Services, US Dept of Health and Human Services; 2018 [cited 2023 Jul 21]. Available from: https://chemtrust.org/pfas/
Feng Y, Bai Y, Lu Y, Chen M, Fu M, Guan X, et al. Plasma perfluoroalkyl substance exposure and incidence risk of breast cancer: A case-cohort study in the Dongfeng-Tongji cohort. Environmental Pollution. 2022 Aug 1;306:119345. https://www.sciencedirect.com/science/article/abs/pii/S0269749122005590
Mancini FR, Cano-Sancho G, Gambaretti J, Marchand P, Boutron-Ruault MC, Severi G, et al. Perfluorinated alkylated substances serum concentration and breast cancer risk: Evidence from a nested case-control study in the French E3N cohort. Int J Cancer [Internet]. 2020 Feb 15 [cited 2023 Jul 21];146(4):917–28. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.32357
Q14. What is an ‘obesogen’?
Darbre PD. Endocrine Disruption and Disorders of Energy Metabolism. Endocrine Disruption and Human Health. 2015 Jan 1;273–85. https://www.sciencedirect.com/science/article/abs/pii/B9780128011393000156
Reproductive factors, natural and synthetic hormones
Q1. Is breast cancer during pregnancy common?
Allouch S, Gupta I, Malik S, Al Farsi HF, Vranic S, Al Moustafa AE. Breast Cancer During Pregnancy: A Marked Propensity to Triple-Negative Phenotype. Front Oncol. 2020 Dec 23;10:580345. https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2020.580345/full
Cancer Research UK. Breast cancer during pregnancy [Internet]. [cited 2023 Jul 24]. Available from: https://www.cancerresearchuk.org/about-cancer/breast-cancer/living-with/breast-cancer-during-pregnancy
Q2. How does age at the birth of a first child affect your breast cancer risk?
Bernstein L. Epidemiology of endocrine-related risk factors for breast cancer. J Mammary Gland Biol Neoplasia [Internet]. 2002 Jan [cited 2023 Jul 24];7(1):3–15. Available from: https://pubmed.ncbi.nlm.nih.gov/12160084/
Ma H, Bernstein L, Pike MC, Ursin G. Reproductive factors and breast cancer risk according to joint estrogen and progesterone receptor status: A meta-analysis of epidemiological studies. Breast Cancer Research [Internet]. 2006 Jul 19 [cited 2023 Jul 24];8(4):1–11. Available from: https://breast-cancer-research.biomedcentral.com/articles/10.1186/bcr1525
Nichols HB, Schoemaker MJ, Cai J, Xu J, Wright LB, Brook MN, et al. Breast cancer risk after recent childbirth: A pooled analysis of 15 prospective studies. Ann Intern Med. 2019 Jan 1;170(1):22–30. https://pubmed.ncbi.nlm.nih.gov/30534999/
Slepicka PF, Cyrill SL, dos Santos CO. Pregnancy and Breast Cancer: Pathways to Understand Risk and Prevention. Trends Mol Med [Internet]. 2019 Oct 1 [cited 2023 Jul 24];25(10):866–81. Available from: http://www.cell.com/article/S1471491419301650/fulltext
Q3. Does breastfeeding reduce the risk of breast cancer?
Fortner RT, Sisti J, Chai B, Collins LC, Rosner B, Hankinson SE, et al. Parity, breastfeeding, and breast cancer risk by hormone receptor status and molecular phenotype: Results from the Nurses’ Health Studies. Breast Cancer Research [Internet]. 2019 Mar 12 [cited 2023 Jul 24];21(1):1–9. Available from: https://breast-cancer-research.biomedcentral.com/articles/10.1186/s13058-019-1119-y
Stordal B. Breastfeeding reduces the risk of breast cancer: A call for action in high-income countries with low rates of breastfeeding. Cancer Med [Internet]. 2023 Feb 1 [cited 2023 Jul 24];12(4):4616–25. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/cam4.5288
World Cancer Research Fund. Lactation (breastfeeding) and the risk of cancer [Internet]. [cited 2023 Jul 24]. Available from: https://www.wcrf.org/dietandcancer/lactation-breastfeeding/
Q4. Does HRT cause breast cancer?
Vinogradova Y, Coupland C, Hippisley-Cox J. Use of hormone replacement therapy and risk of breast cancer: nested case-control studies using the QResearch and CPRD databases. BMJ [Internet]. 2020 Oct 28 [cited 2023 Jul 27];371. Available from: https://www.bmj.com/content/371/bmj.m3873
Q5. Is it true that I’m more at risk if I don’t have children?
Britt K, Ashworth A, Smalley M. Pregnancy and the risk of breast cancer. Endocr Relat Cancer [Internet]. 2007 Dec [cited 2023 Jul 27];14(4):907–33. Available from: https://pubmed.ncbi.nlm.nih.gov/18045947/
Husby A, Wohlfahrt J, Øyen N, Melbye M. Pregnancy duration and breast cancer risk. Nat Commun [Internet]. 2018 Dec 1 [cited 2023 Jul 27];9(1). Available from: https://pubmed.ncbi.nlm.nih.gov/30353005/
Q6. If I’m on a contraceptive pill or another type of hormonal contraception, am I at increased breast cancer risk?
Conz L, Mota BS, Bahamondes L, Teixeira Dória M, Françoise Mauricette Derchain S, Rieira R, et al. Levonorgestrel-releasing intrauterine system and breast cancer risk: A systematic review and meta-analysis. Acta Obstet Gynecol Scand [Internet]. 2020 Aug 1 [cited 2023 Jul 27];99(8):970–82. Available from: https://pubmed.ncbi.nlm.nih.gov/31990981/
Fitzpatrick D, Pirie K, Reeves G, Green J, Beral V. Combined and progestagen-only hormonal contraceptives and breast cancer risk: A UK nested case–control study and meta-analysis. PLoS Med [Internet]. 2023 Mar 1 [cited 2023 Jul 27];20(3):e1004188. Available from: https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1004188
Karlsson T, Johansson T, Hoglund J, Ek WE, Johansson Å. Time-dependent effects of oral contraceptive use on breast, ovarian, and endometrial cancers. Cancer Res [Internet]. 2021 Feb 15 [cited 2023 Jul 27];81(4):1153–62. Available from: https://dx.doi.org/10.1158/0008-5472.CAN-20-2476
Samson M, Porter N, Orekoya O, Hebert JR, Adams SA, Bennett CL, et al. Progestin and breast cancer risk: a systematic review. Breast Cancer Res Treat [Internet]. 2016 Jan 1 [cited 2023 Jul 27];155(1):3–12. Available from: https://link.springer.com/article/10.1007/s10549-015-3663-1
Silva FR, Grande AJ, Lacerda Macedo AC, Colonetti T, Rocha MC, Rodrigues Uggioni ML, et al. Meta-Analysis of Breast Cancer Risk in Levonorgestrel-Releasing Intrauterine System Users. Clin Breast Cancer [Internet]. 2021 Dec 1 [cited 2023 Jul 27];21(6):497–508. Available from: https://pubmed.ncbi.nlm.nih.gov/34045174/
Q7. Why are high levels of oestrogen potentially harmful?
Santen RJ, Yue W, Wang JP. Estrogen metabolites and breast cancer. Steroids [Internet]. 2015 May 26 [cited 2023 Jul 27];99(Pt A):61–6. Available from: https://pubmed.ncbi.nlm.nih.gov/25168343/
Travis RC, Key TJ. Oestrogen exposure and breast cancer risk. Breast Cancer Res [Internet]. 2003 [cited 2023 Jul 27];5(5):239. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC314432/
Q8. Do transgender women have an increased risk of breast cancer?
De Blok CJM, Wiepjes CM, Nota NM, Van Engelen K, Adank MA, Dreijerink KMA, et al. Breast cancer risk in transgender people receiving hormone treatment: nationwide cohort study in the Netherlands. BMJ [Internet]. 2019 [cited 2023 Jul 27];365. Available from: https://pubmed.ncbi.nlm.nih.gov/31088823/
Iwamoto SJ, Defreyne J, Rothman MS, Van Schuylenbergh J, Van de Bruaene L, Motmans J, et al. Health considerations for transgender women and remaining unknowns: a narrative review. Ther Adv Endocrinol Metab [Internet]. 2019 [cited 2023 Jul 27];10. Available from: https://pubmed.ncbi.nlm.nih.gov/31516689/
Q9. Do transgender men have an increased risk of breast cancer?
De Blok CJM, Wiepjes CM, Nota NM, Van Engelen K, Adank MA, Dreijerink KMA, et al. Breast cancer risk in transgender people receiving hormone treatment: nationwide cohort study in the Netherlands. BMJ [Internet]. 2019 [cited 2023 Jul 27];365. Available from: https://pubmed.ncbi.nlm.nih.gov/31088823/
Fledderus AC, Gout HA, Ogilvie AC, Van Loenen DKG. Breast malignancy in female-to-male transsexuals: systematic review, case report, and recommendations for screening. The Breast [Internet]. 2020 [cited 2023 Jul 27];53:92–100. Available from: https://doi.org/10.1016/j.breast.2020.06.008
Genetics and family history
Q1. Are there any ethnic groups in the UK more at risk of breast cancer?
Gathani T, Ali R, Balkwill A, Green J, Reeves G, Beral V, et al. Ethnic differences in breast cancer incidence in England are due to differences in known risk factors for the disease: prospective study. Br J Cancer [Internet]. 2014 Jan 1 [cited 2023 Jul 27];110(1):224. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3887283/
Gathani T, Reeves G, Broggio J, Barnes I. Ethnicity and the tumour characteristics of invasive breast cancer in over 116,500 women in England. British Journal of Cancer 2021 125:4 [Internet]. 2021 May 26 [cited 2023 Jul 27];125(4):611–7. Available from: https://www.nature.com/articles/s41416-021-01409-7
Haiman CA, Chen GK, Vachon CM, Canzian F, Dunning A, Millikan RC, et al. A common variant at the TERT-CLPTM1L locus is associated with estrogen receptor-negative breast cancer. Nat Genet [Internet]. 2011 Dec [cited 2023 Jul 27];43(12):1210–4. Available from: https://pubmed.ncbi.nlm.nih.gov/22037553/
KB K, JL H, DR B, KA P, TM M, MJ RB, et al. Risks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers. JAMA [Internet]. 2017 Jun 20 [cited 2023 Jul 27];317(23):2402–16. Available from: https://pubmed.ncbi.nlm.nih.gov/28632866/
Manchanda R, Loggenberg K, Sanderson S, Burnell M, Wardle J, Gessler S, et al. Population testing for cancer predisposing BRCA1/BRCA2 mutations in the Ashkenazi-Jewish community: a randomized controlled trial. J Natl Cancer Inst [Internet]. 2014 Jan 1 [cited 2023 Jul 27];107(1). Available from: https://pubmed.ncbi.nlm.nih.gov/25435541/
Shirley MH, Barnes I, Sayeed S, Finlayson A, Ali R. Incidence of breast and gynaecological cancers by ethnic group in England, 2001-2007: A descriptive study. BMC Cancer [Internet]. 2014 Dec 18 [cited 2023 Jul 27];14(1):1–10. Available from: https://bmccancer.biomedcentral.com/articles/10.1186/1471-2407-14-979
Q2. Does a family history of breast cancer put someone at a higher risk?
Economopoulou P, Dimitriadis G, Psyrri A. Beyond BRCA: New hereditary breast cancer susceptibility genes. Cancer Treat Rev [Internet]. 2015 Jan 1 [cited 2023 Jul 27];41(1):1–8. Available from: http://www.cancertreatmentreviews.com/article/S0305737214001741/fulltext
Q3. What are BRCA1 and BRCA2 genes?
National Cancer Institute. BRCA Gene Mutations: Cancer Risk and Genetic Testing Fact Sheet [Internet]. 2020 [cited 2023 Jul 27]. Available from: https://www.cancer.gov/about-cancer/causes-prevention/genetics/brca-fact-sheet#what-are-brca1-and-brca2
The Royal Marsden NHS Foundation Trust. A beginner’s guide to BRCA1 and BRCA2. 2013.
National Cancer Institute (2020) BRCA Gene Mutations: Cancer Risk and Genetic Testing. https://shared-d7-royalmarsden-publicne-live.s3-eu-west-1.amazonaws.com/files_trust/s3fs-public/GE-1200-05 Guide to BRCA1 BRCA2 A5_Aug2019 FINAL.PDF
Q4. Is there a connection between breast cancer and ovarian cancer and are the causes the same?
Genomics Education Programme. Hereditary breast and ovarian cancer [Internet]. 2020 [cited 2023 Jul 27]. Available from: https://www.genomicseducation.hee.nhs.uk/documents/hereditary-breast-and-ovarian-cancer/
Cancer.Net. Hereditary Breast and Ovarian Cancer [Internet]. 2020 [cited 2023 Jul 27]. Available from: https://www.cancer.net/cancer-types/hereditary-breast-and-ovarian-cancer
Q5. Why are taller women at a higher risk of getting breast cancer?
Zhang B, Shu XO, Delahanty RJ, Zeng C, Michailidou K, Bolla MK, et al. Height and Breast Cancer Risk: Evidence From Prospective Studies and Mendelian Randomization. J Natl Cancer Inst [Internet]. 2015 Nov 1 [cited 2023 Jul 27];107(11). Available from: https://pubmed.ncbi.nlm.nih.gov/26296642/
Other frequently asked questions
Q1. Does having larger breasts increase the risk of breast cancer?
Hsieh C c, Trichopoulos D. Breast size, handedness and breast cancer risk. Eur J Cancer Clin Oncol. 1991 Jan 1;27(2):131–5. https://www.sciencedirect.com/science/article/abs/pii/027753799190469T?via%3Dihub
Ooi BNS, Loh H, Ho PJ, Milne RL, Giles G, Gao C, et al. The genetic interplay between body mass index, breast size and breast cancer risk: a Mendelian randomization analysis. Int J Epidemiol [Internet]. 2019 Jun 1 [cited 2023 Jul 27];48(3):781–94. Available from: https://academic.oup.com/ije/article/48/3/781/5523691
Sellahewa C, Nightingale P, Carmichael AR. Women with large breasts are at an increased risk of advanced breast cancer. International Seminars in Surgical Oncology [Internet]. 2008 Jun 30 [cited 2023 Jul 27];5(1):1–4. Available from: https://issoonline.biomedcentral.com/articles/10.1186/1477-7800-5-16
Q2. Am I more at risk of breast cancer if I have breast implants?
Brett EA, Aitzetmüller MM, Sauter MA, Huemer GM, Machens HG, Duscher D. Breast cancer recurrence after reconstruction: know thine enemy. Oncotarget [Internet]. 2018 Jun 12 [cited 2023 Jul 27];9(45):27895–906. Available from: https://pubmed.ncbi.nlm.nih.gov/29963246/
Jones JL, Hanby AM, Wells C, Calaminici M, Johnson L, Turton P, et al. Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL): an overview of presentation and pathogenesis and guidelines for pathological diagnosis and management. Histopathology [Internet]. 2019 Dec 1 [cited 2023 Jul 27];75(6):787–96. Available from: https://onlinelibrary.wiley.com/doi/full/10.1111/his.13932
Noels EC, Lapid O, Lindeman JHN, Bastiaannet E. Breast implants and the risk of breast cancer: a meta-analysis of cohort studies. Aesthet Surg J [Internet]. 2015 Jan 1 [cited 2023 Jul 27];35(1):55–62. Available from: https://pubmed.ncbi.nlm.nih.gov/25568234/
Q3. Is stress a risk factor for breast cancer?
Chiriac VF, Baban A, Dumitrascu DL. Psychological stress and breast cancer incidence: a systematic review. Clujul Med [Internet]. 2018 [cited 2023 Jul 27];91(1):18–26. Available from: https://pubmed.ncbi.nlm.nih.gov/29440947/
Cancer Research UK. Can stress cause cancer? [Internet]. [cited 2023 Jul 27]. Available from: https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/cancer-myths/can-stress-cause-cancer
Mohan A, Huybrechts I, Michels N. Psychosocial stress and cancer risk: a narrative review. Eur J Cancer Prev [Internet]. 2022 Nov 1 [cited 2023 Jul 27];31(6):585–99. Available from: https://pubmed.ncbi.nlm.nih.gov/35352705/
Pereira MA, Araújo A, Simões M, Costa C. Influence of Psychological Factors in Breast and Lung Cancer Risk – A Systematic Review. Front Psychol [Internet]. 2022 Jan 3 [cited 2023 Jul 27];12. Available from: https://pubmed.ncbi.nlm.nih.gov/35046872/
Schoemaker MJ, Jones ME, Wright LB, Griffin J, McFadden E, Ashworth A, et al. Psychological stress, adverse life events and breast cancer incidence: a cohort investigation in 106,000 women in the United Kingdom. Breast Cancer Res [Internet]. 2016 Jul 15 [cited 2023 Jul 27];18(1). Available from: https://pubmed.ncbi.nlm.nih.gov/27418063/
Q4. What does it mean to have dense breasts – is this a risk?
Sprague BL, Trentham-Dietz A, Hedman CJ, Wang J, Hemming JDC, Hampton JM, et al. Circulating serum xenoestrogens and mammographic breast density. Breast Cancer Research [Internet]. 2013 May 27 [cited 2023 Jul 27];15(3):1–8. Available from: https://breast-cancer-research.biomedcentral.com/articles/10.1186/bcr3432
Q6. Does chlorine in drinking water increase breast cancer risk?
IARC Working Group on the Evaluation of Carcinogenic Risks to Humans., International Agency for Research on Cancer. Some Chemicals that Cause Tumours of the Kidney or Urinary Bladder in Rodents and Some Other Substances. World Health Organization, International Agency for Research on Cancer; 1999. https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Some-Chemicals-That-Cause-Tumours-Of-The-Kidney-Or-Urinary-Bladder-In-Rodents-And-Some-Other-Substances-1999
Q7. Can mammograms increase the risk of breast cancer?
GOV.UK. NHS breast screening: helping you decide [Internet]. 2021 [cited 2023 Jul 27]. Available from: https://www.gov.uk/government/publications/breast-screening-helping-women-decide/nhs-breast-screening-helping-you-decide
Q8. Does socioeconomic status affect your risk of breast cancer?
Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin [Internet]. 2021 May 1 [cited 2023 Jul 27];71(3):209–49. Available from: https://onlinelibrary.wiley.com/doi/full/10.3322/caac.21660
Q9. Does where you live affect your risk of breast cancer?
Sharp L, Donnelly D, Hegarty A, Carsin AE, Deady S, McCluskey N, et al. Risk of several cancers is higher in urban areas after adjusting for socioeconomic status. Results from a two-country population-based study of 18 common cancers. J Urban Health [Internet]. 2014 [cited 2023 Jul 27];91(3):510–25. Available from: https://pubmed.ncbi.nlm.nih.gov/24474611/
National Cancer Registration and Analysis Service. The effect of rurality on cancer incidence and mortality [Internet]. [cited 2023 Jul 27]. Available from: http://www.ncin.org.uk/publications/data_briefings/rurality
Q10. Do underwire bras increase my risk of breast cancer?
Chen L, Malone KE, Li CI. Bra wearing not associated with breast cancer risk: A population-based case-control study. Cancer Epidemiology Biomarkers and Prevention [Internet]. 2014 Oct 1 [cited 2023 Jul 27];23(10):2181–5. Available from: https://dx.doi.org/10.1158/1055-9965.EPI-14-0414
Q11. Does night shift work increase breast cancer risk?
Gehlert S, Clanton M, Group on behalf of the SW and BCSA. Shift Work and Breast Cancer. Int J Environ Res Public Health [Internet]. 2020 Dec 2 [cited 2023 Jul 27];17(24):1–8. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767214/
Hill SM, Belancio VP, Dauchy RT, Xiang S, Brimer S, Mao L, et al. Melatonin: an inhibitor of breast cancer. Endocr Relat Cancer [Internet]. 2015 Jun 1 [cited 2023 Jul 27];22(3):R183–204. Available from: https://pubmed.ncbi.nlm.nih.gov/25876649/
IARC Monographs Vol 124 group. Carcinogenicity of night shift work. Lancet Oncol [Internet]. 2019 Aug 1 [cited 2023 Jul 27];20(8):1058–9. Available from: https://pubmed.ncbi.nlm.nih.gov/31281097/
Liu FC, Veierød MB, Kjærheim K, Robsahm TE, Ghiasvand R, Babigumira R, et al. Excess risk of male breast cancer in the Norwegian Offshore Petroleum Workers (NOPW) cohort: a possible link to extreme night shift work? Breast Cancer Res [Internet]. 2021 Dec 1 [cited 2023 Jul 27];23(1). Available from: https://pubmed.ncbi.nlm.nih.gov/34794511/
Lopes J, Arnosti D, Trosko JE, Tai MH, Zuccari D. Melatonin decreases estrogen receptor binding to estrogen response elements sites on the oct4 gene in human breast cancer stem cells. Genes Cancer [Internet]. 2016 May 1 [cited 2023 Jul 27];7(5–6):209–17. Available from: https://www.genesandcancer.com/article/107/text/
Manouchehri E, Taghipour A, Ghavami V, Ebadi A, Homaei F, Latifnejad Roudsari R. Night-shift work duration and breast cancer risk: an updated systematic review and meta-analysis. BMC Womens Health [Internet]. 2021 Dec 1 [cited 2023 Jul 27];21(1):1–16. Available from: https://bmcwomenshealth.biomedcentral.com/articles/10.1186/s12905-021-01233-4
Jones ME, Schoemaker MJ, McFadden EC, Wright LB, Johns LE, Swerdlow AJ. Night shift work and risk of breast cancer in women: the Generations Study cohort. British Journal of Cancer. 2019 Jul [cited 2024 May 22];121(2):172-179. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6738051/
Q12. Does mobile phone use increase breast cancer risk?
Röösli M, Lagorio S, Schoemaker MJ, Schüz J, Feychting M. Brain and Salivary Gland Tumors and Mobile Phone Use: Evaluating the Evidence from Various Epidemiological Study Designs. Annu Rev Public Health [Internet]. 2019 Apr 1 [cited 2023 Jul 27];40:221–38. Available from: https://pubmed.ncbi.nlm.nih.gov/30633716/
Schüz J, Jacobsen R, Olsen JH, Boice JD, McLaughlin JK, Johansen C. Cellular telephone use and cancer risk: update of a nationwide Danish cohort. J Natl Cancer Inst [Internet]. 2006 Dec 6 [cited 2023 Jul 27];98(23):1707–13. Available from: https://pubmed.ncbi.nlm.nih.gov/17148772/
West JG, Kapoor NS, Liao SY, Chen JW, Bailey L, Nagourney RA. Multifocal Breast Cancer in Young Women with Prolonged Contact between Their Breasts and Their Cellular Phones. Case Rep Med [Internet]. 2013 [cited 2023 Jul 27];2013. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789302/
Q13. Does having type 2 diabetes increase breast cancer risk?
Diabetes.co.uk. Breast Cancer and Diabetes [Internet]. 2019 [cited 2023 Jul 27]. Available from: https://www.diabetes.co.uk/diabetes-complications/breast-cancer.html
Hardefeldt PJ, Edirimanne S, Eslick GD. Diabetes increases the risk of breast cancer: a meta-analysis. Endocr Relat Cancer [Internet]. 2012 Dec 1 [cited 2023 Jul 27];19(6):793–803. Available from: https://erc.bioscientifica.com/view/journals/erc/19/6/793.xml
Lu Y, Hajjar A, Cryns VL, Trentham-Dietz A, Gangnon RE, Heckman-Stoddard BM, et al. Breast cancer risk for women with diabetes and the impact of metformin: A meta-analysis. Cancer Med [Internet]. 2023 May 1 [cited 2023 Jul 27];12(10):11703–18. Available from: https://pubmed.ncbi.nlm.nih.gov/36533539/
Last Review: April 2024
Next Review: April 2025
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