Are you susceptible?

Yes, you are susceptible…

But your risk of getting breast cancer is dependent on many factors.  Some are related to your genes. Others depend on what happened to you in the womb and growing up, your environment, and how you live your life now.  Whatever your susceptibility, you can help yourself by adopting strategies, like maintaining a healthy diet or changing your lifestyle, to give yourself the greatest protection possible.

Although uncommon, men can also develop breast cancer. Several, but not all, risk factors are common to both men and women. Please see here for a link to our background briefing which discusses breast cancer in men.

Some of the factors which influence your susceptibility

Physical make-up 

• Being a woman means having more breast tissue that is susceptible to breast cancer and a higher lifetime exposure to oestrogens, which can stimulate cell division and growth and promote the growth of certain types of breast tumours.
• Age is the most significant risk factor for female and male breast cancer. As you age, mutations accumulate in your cells, including those that increase your risk of cancers, including breast cancer.
• A history of certain types of benign breast disease or a previous breast cancer diagnosis means you have an increased risk of breast cancer. Breast cancers commonly occur in women with atypical hyperplasia and proliferative disease without atypia. Two types of non-invasive breast cancer, lobular carcinoma in situ and ductal carcinoma in situ, are also associated with an increased risk of breast cancer.
• High breast density is the most significant risk factor for breast cancer after being a woman and age. Breast density (also known as mammographic density) can only be identified by a mammogram (breast X-ray) and is partly genetic and partly influenced by environment and changes over a lifetime.
• Starting your periods early (before 12) or reaching menopause late (after 55) are factors that contribute to a higher risk of breast cancer. This is thought to be related to the longer time period that high concentrations of oestrogens are circulating in your body.
• Being tall can make you more susceptible, possibly due to the higher levels of growth hormone and certain growth factors in your body during early development.
• A birth weight above 4kg and large early body size before the age of 18 means you are at an increased lifetime risk of developing breast cancer. 
• Higher levels of naturally circulating sex hormones (oestrogen, progesterone and testosterone) increases breast cancer risk. Post-menopausal women with higher levels of naturally circulating oestrogen have around twice the risk of breast cancer compared to those with lower levels.

Environment

• Radiation exposure as a result of radiotherapy for medical treatment, or from other high-energy sources (for example nuclear fallout, multiple chest X-rays), particularly during puberty, can damage your DNA which increases your risk of mutations and chances of developing breast cancer.
• Environmental carcinogens present in polluted air (for example dioxins and polychlorinated hydrocarbons), or as a result of working in hazardous occupations, can increase breast cancer risk.
• Endocrine Disrupting Chemicals (EDCs) which are found in many everyday products can mimic, block, or interfere with hormones in the body and may influence the development of breast cancer.
• Exposure to diethylstilboestrol (DES) during pregnancy or in utero. DES is a synthetic oestrogen and EDC, which was used as an anti-miscarriage drug until the 1970s. Women who took DES, along with their daughters, have a higher risk of breast cancer.
• Air pollution contains carcinogens, EDCs and particulate matter (fine particles 10 micrometres or less in size) which may contribute to increased breast cancer risk.
• Where you live affects your breast cancer risk. The highest rates of breast cancer occur in North and Western Europe, Australia, New Zealand, Canada and the US. The lowest rates are found in Eastern Asia and South America. In the UK and other countries, living in urban areas, as opposed to rural areas, is associated with an increased risk of breast cancer.

Lifestyle 

• Having children after the age of 30 or having no children puts you at greater risk of breast cancer. Having more children at a young age reduces your risk.
• Breastfeeding reduces your risk and the longer you breastfeed the more your risk is decreased.
• Being overweight and adult weight gain are well-recognised risk factors for breast cancer in post-menopausal women, mainly due to increased levels of circulating oestrogens.
• Lack of physical activity is a risk factor because physical activity helps lower levels of certain growth factors and hormones, including oestrogen – higher levels of these are associated with cancer development and progression.
• Drinking alcohol increases your risk; this is thought to be because alcohol can raise the concentration of circulating oestrogens, also, alcohol is broken down in breast tissue to produce by-products which may damage DNA.
• Shift work or exposure to light at night may increase breast cancer risk. Both may be responsible for decreased production of melatonin, a hormone which is protective against breast cancer.
• Smoking especially if you begin at an early age or have smoked for many years, increases your risk.
• Use of the contraceptive pill and implants (combined synthetic oestrogen and progesterone) increase breast cancer risk slightly. Risk increases with a longer duration of use and is no longer apparent 5-10 years after use has ceased.
• Use of combined Hormone Replacement Therapy (synthetic oestrogen and progesterone) carries an increased risk especially if you use it over a long period. This risk decreases following cessation of use and is less, or no longer apparent for short-term users, 5-10 years after use has stopped. HRT containing oestrogen alone may be associated with a slight increase in risk.

Genes and family background

• Family History of breast cancer is relevant but as breast cancer is common, having a relative with the disease doesn’t necessarily indicate you have a genetic predisposition. Having a first-degree relative (mother, sibling or daughter) who has developed breast cancer (especially at a young age) approximately doubles your risk.
• Single gene mutations such as BRCA1 and BRCA2 are uncommon and account for around 4% of breast cancers.  Recent studies suggest the risk of getting breast cancer by the time you reach 80 if you carry a faulty BRCA1 or BRCA2 gene is around 70%. See the NHS website for comprehensive advice about genetic testing.
• Genetic variation in multiple genes and other regions of DNA is also associated with an increased breast cancer risk. Genetic variation (including single-gene mutations) is thought to account for around a fifth of all breast cancers.

Last Review: August 2019