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Smoking means you inhale a number of cancer causing chemicals, like polycyclic aromatic hydrocarbons, which are known to cause breast cancer.
Your risk of breast cancer from smoking is higher if you started smoking early and you have not reached the menopause.
The best solution is to try to give up!
There is lots of support from your local NHS to give up smoking.
For help with quitting visit the NHS website, or contact your local general practitioner.
Having children early (under 30) reduces your risk of breast cancer.Having more children, at a younger age, also reduces risk. Although the risk of breast cancer increases after having children, and peaks around 5 years after child-birth, the long-term protective effects of having children early outweigh this risk.
Breastfeeding your child gives you some protection against breast cancer, and the longer you do it the more you benefit – it is especially protective against developing hormone receptor negative breast cancer.
Most studies link combined oral contraceptives to a small increase in breast cancer risk. A recent Danish study of nearly two million women found a 20% increase in risk of breast cancer among current or recent users, compared to non-users. Increased risk was mainly associated with contraceptives containing combined synthetic oestrogen and progesterone.
Your risk goes up the longer you use the combined pill and decreases when you stop taking it, with risk no longer apparent five years after use has stopped. Intrauterine devices (IUDs), injections or other forms of combined hormonal contraception are also thought to increase risk.
It’s unclear whether hormonal contraceptives that contain progestin only (synthetic progesterone) increase risk, as results of studies vary.
Discuss with your doctor what birth control alternatives are available.
The NHS website has some further information on types of contraception.
There is an increased breast cancer risk whilst taking combined HRT (synthetic oestrogen and progesterone), and this increases the longer you take it. The risk lowers considerably when you stop taking it, although some excess risk persists for more than 10 years after stopping its use. Most studies have found oestrogen-only HRT is associated with a small increase, or no, change in breast cancer risk, although this type of therapy may not be suitable for all women.
Discuss with your doctor what choices you have for alternative approaches to managing menopausal symptoms. The NHS website has further information on Hormone Replacement Therapy.
Night shift work and light at night exposure are thought to be risk factors for breast cancer, though not all studies support this finding.
Different assessments of what constitutes night shift work or different amounts of night light exposure may help explain the disparity in findings.
Night-time shift work and its correlation with increased breast cancer may be due to lower melatonin production (a hormone associated with circadian rhythm) which is associated with elevated breast cancer risk.
If possible, try to avoid long periods of shift work and aim to get some good quality sleep in a dark room, preferably at night.
Low levels of vitamin D have been found in people with breast cancer.
It is unclear whether a low level of vitamin D increases risk, or whether breast cancer itself causes vitamin D levels to drop. Either way addressing this issue may be beneficial.
Ensure you are getting a healthy amount of vitamin D. Some can be obtained from – your diet (for example oily fish and egg yolks), but most is made by your body during exposure to sunlight. If you have any concerns ask your doctor to check your levels and, if they are low, try to get some sunlight on your skin, especially from March to September (see the NHS for advice). This will help your vitamin D levels remain at an adequate level throughout the winter.
Use this online calculator to work out how much time you need in the sun to get any dose of vitamin D3. It lets you enter all the factors that could influence your UVB exposure.
Islami, F. et al. (2015). Breastfeeding and breast cancer risk by receptor status – a systematic review and meta-analysis. Annals of Oncology 26: 2398–2407. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4855244/pdf/mdv379.pdf
Victoria, C. G. et al. (2016). Breastfeeding into the 21st Century: epidemiology, mechanisms, and lifelong effect. The Lancet 387: 475-490. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(15)01024-7/fulltext
Pup, L. D. et al. (2019). Breast cancer risk of hormonal contraception: Counselling considering new evidence. Critical Reviews in Oncology/Hematology 137: 123-130. https://www.sciencedirect.com/science/article/abs/pii/S1040842818302208?via%3Dihub
Mørch L.S. et al. (2017). Contemporary Hormonal Contraception and the Risk of Breast Cancer. The New England Journal of Medicine 377(23): 2228-2239. https://www.nejm.org/doi/full/10.1056/nejmoa1700732
Collaborative Group on Hormonal Factors in Breast Cancer (2019). Type and timing of menopausal hormone therapy and breast cancer risk: individual participant meta-analysis of the worldwide epidemiological evidence. The Lancet 394: 1159-1168. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)31709-X/fulltext
Jones C. et al. (2017). Smoking and the risk of breast cancer in the generations study cohort. Breast Cancer Research 19(1): 118. https://www.ncbi.nlm.nih.gov/pubmed/29162146
Macacu, A. et al. (2015). Active and passive smoking and risk of breast cancer: a meta-analysis. Breast Cancer Research and Treatment 154(2): 213–224. https://www.ncbi.nlm.nih.gov/pubmed/26546245
van der Brandt, P. (2017). A possible dual effect of cigarette smoking on the risk of postmenopausal breast cancer. European Journal of Epidemiology 32: 683-690. https://www.ncbi.nlm.nih.gov/pubmed/28710542
Cancer Research UK (2018). How does smoking cause cancer? https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/smoking-and-cancer/how-does-smoking-cause-cancer#smoking_facts1 (Accessed 22.4.19)
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