Editing Breast cancer (section)

=== Lifestyle ===
{{See also|Alcohol and breast cancer|Risk factors for breast cancer}}

[[File:NIH standard drink comparison.jpg|upright=1.2|alt=Diagram of different sizes, showing how big a single serving of alcohol is for different types of alcoholic beverages|thumb|All types of [[alcoholic beverage]]s, including beer, wine, or liquor, cause breast cancer.]]

Drinking [[alcoholic beverage]]s increases the risk of breast cancer, even among very light drinkers (women drinking less than half of one alcoholic drink per day).<ref name="Choi">{{cite journal | vauthors = Choi YJ, Myung SK, Lee JH | title = Light Alcohol Drinking and Risk of Cancer: A Meta-Analysis of Cohort Studies | journal = Cancer Research and Treatment | volume = 50 | issue = 2 | pages = 474–487 | date = April 2018 | pmid = 28546524 | pmc = 5912140 | doi = 10.4143/crt.2017.094 }}</ref> The risk is highest among heavy drinkers.<ref name="Shield">{{cite journal | vauthors = Shield KD, Soerjomataram I, Rehm J | title = Alcohol Use and Breast Cancer: A Critical Review | journal = Alcoholism: Clinical and Experimental Research | volume = 40 | issue = 6 | pages = 1166–1181 | date = June 2016 | pmid = 27130687 | doi = 10.1111/acer.13071 | quote = All levels of evidence showed a risk relationship between alcohol consumption and the risk of breast cancer, even at low levels of consumption. }}</ref> Globally, about one in ten cases of breast cancer is caused by women drinking alcoholic beverages.<ref name="Shield" /> Alcohol use is among the most common modifiable risk factors.<ref>{{cite journal | vauthors = McDonald JA, Goyal A, Terry MB | title = Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence | journal = Current Breast Cancer Reports | volume = 5 | issue = 3 | pages = 208–221 | date = September 2013 | pmid = 24265860 | pmc = 3832299 | doi = 10.1007/s12609-013-0114-z }}</ref>

[[Obesity]] and [[diabetes]] increase the risk of breast cancer. A high [[body mass index]] (BMI) causes 7% of breast cancers while diabetes is responsible for 2%.<ref name="NIHR Evidence_2023">{{cite news |title=Why we need to understand breast cancer risk |date=5 October 2023 |doi=10.3310/nihrevidence_60242 }}</ref><ref>{{cite journal | vauthors = Pearson-Stuttard J, Zhou B, Kontis V, Bentham J, Gunter MJ, Ezzati M | title = Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment | journal = The Lancet. Diabetes & Endocrinology | volume = 6 | issue = 6 | pages = e6–e15 | date = June 2018 | pmid = 29803268 | pmc = 5982644 | doi = 10.1016/S2213-8587(18)30150-5 }}</ref> At the same time the correlation between obesity and breast cancer is not at all linear. Studies show that those who rapidly gain weight in adulthood are at higher risk than those who have been overweight since childhood. Likewise, excess fat in the [[midriff]] seems to induce a higher risk than excess weight carried in the lower body.<ref>{{cite web|title=Lifestyle-related Breast Cancer Risk Factors|url=https://www.cancer.org/cancer/breast-cancer/risk-and-prevention/lifestyle-related-breast-cancer-risk-factors.html|website=[[American Cancer Society]]|access-date=18 April 2018|archive-date=27 July 2020|archive-url=https://web.archive.org/web/20200727075717/https://www.cancer.org/cancer/breast-cancer/risk-and-prevention/lifestyle-related-breast-cancer-risk-factors.html|url-status=live}}</ref> Dietary factors that may increase risk include a high-fat diet<ref>{{cite journal | vauthors = Blackburn GL, Wang KA | title = Dietary fat reduction and breast cancer outcome: results from the Women's Intervention Nutrition Study (WINS) | journal = The American Journal of Clinical Nutrition | volume = 86 | issue = 3 | pages = s878-81 | date = September 2007 | pmid = 18265482 | doi = 10.1093/ajcn/86.3.878S | doi-access = free }}</ref> and obesity-related [[high cholesterol]] levels.<ref>{{cite web|work=BBC News|url=http://news.bbc.co.uk/1/hi/health/5171838.stm |title=Weight link to breast cancer risk |date=12 July 2006 |archive-url=https://web.archive.org/web/20070313141518/http://news.bbc.co.uk/1/hi/health/5171838.stm |archive-date=13 March 2007 }}</ref><ref>{{cite journal | vauthors = Kaiser J | title = Cancer. Cholesterol forges link between obesity and breast cancer | journal = Science | volume = 342 | issue = 6162 | pages = 1028 | date = November 2013 | pmid = 24288308 | doi = 10.1126/science.342.6162.1028 }}</ref>

Dietary iodine deficiency may also play a role in the development of breast cancer.<ref>{{cite journal | vauthors = Aceves C, Anguiano B, Delgado G | title = Is iodine a gatekeeper of the integrity of the mammary gland? | journal = Journal of Mammary Gland Biology and Neoplasia | volume = 10 | issue = 2 | pages = 189–96 | date = April 2005 | pmid = 16025225 | doi = 10.1007/s10911-005-5401-5 }}</ref>

[[Smoking tobacco]] appears to increase the risk of breast cancer, with the greater the amount smoked and the earlier in life that smoking began, the higher the risk.<ref name="Smoking2011">{{cite journal | vauthors = Johnson KC, Miller AB, Collishaw NE, Palmer JR, Hammond SK, Salmon AG, Cantor KP, Miller MD, Boyd NF, Millar J, Turcotte F | title = Active smoking and secondhand smoke increase breast cancer risk: the report of the Canadian Expert Panel on Tobacco Smoke and Breast Cancer Risk (2009) | journal = Tobacco Control | volume = 20 | issue = 1 | pages = e2 | date = January 2011 | pmid = 21148114 | doi = 10.1136/tc.2010.035931 }}</ref> In those who are long-term smokers, the relative risk is increased by 35% to 50%.<ref name="Smoking2011" />

A lack of physical activity has been linked to about 10% of cases.<ref>{{cite journal | vauthors = Lee IM, Shiroma EJ, Lobelo F, Puska P, Blair SN, Katzmarzyk PT | title = Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy | journal = Lancet | volume = 380 | issue = 9838 | pages = 219–29 | date = July 2012 | pmid = 22818936 | pmc = 3645500 | doi = 10.1016/S0140-6736(12)61031-9 }}</ref> [[Sitting]] regularly for prolonged periods is associated with higher mortality from breast cancer. The risk is not negated by regular exercise, though it is lowered.<ref name="Biswas">{{cite journal | vauthors = Biswas A, Oh PI, Faulkner GE, Bajaj RR, Silver MA, Mitchell MS, Alter DA | title = Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis | journal = Annals of Internal Medicine | volume = 162 | issue = 2 | pages = 123–32 | date = January 2015 | pmid = 25599350 | doi = 10.7326/M14-1651 }}</ref>

Actions to prevent breast cancer include not drinking [[alcoholic beverages]], maintaining a healthy [[body composition]], avoiding [[smoking]] and eating [[Healthy diet|healthy food]]. Combining all of these (leading the healthiest possible lifestyle) would make almost a quarter of breast cancer cases worldwide preventable.<ref name="Zhang_2020">{{cite journal | vauthors = Zhang YB, Pan XF, Chen J, Cao A, Zhang YG, Xia L, Wang J, Li H, Liu G, Pan A | title = Combined lifestyle factors, incident cancer, and cancer mortality: a systematic review and meta-analysis of prospective cohort studies | journal = British Journal of Cancer | volume = 122 | issue = 7 | pages = 1085–1093 | date = March 2020 | pmid = 32037402 | pmc = 7109112 | doi = 10.1038/s41416-020-0741-x }}</ref> The remaining three-quarters of breast cancer cases cannot be prevented through lifestyle changes.<ref name="Zhang_2020" />

Other risk factors include [[circadian]] disruptions related to [[shift-work]]<ref>{{cite journal | vauthors = Wang XS, Armstrong ME, Cairns BJ, Key TJ, Travis RC | title = Shift work and chronic disease: the epidemiological evidence | journal = Occupational Medicine | volume = 61 | issue = 2 | pages = 78–89 | date = March 2011 | pmid = 21355031 | pmc = 3045028 | doi = 10.1093/occmed/kqr001 }}</ref> and routine late-night eating.<ref>{{cite journal | vauthors = Marinac CR, Nelson SH, Breen CI, Hartman SJ, Natarajan L, Pierce JP, Flatt SW, Sears DD, Patterson RE | title = Prolonged Nightly Fasting and Breast Cancer Prognosis | journal = JAMA Oncology | volume = 2 | issue = 8 | pages = 1049–55 | date = August 2016 | pmid = 27032109 | pmc = 4982776 | doi = 10.1001/jamaoncol.2016.0164 }}</ref> A number of chemicals have also been linked, including [[polychlorinated biphenyl]]s, [[polycyclic aromatic hydrocarbon]]s, and [[organic solvents]].<ref>{{cite journal | vauthors = Brody JG, Rudel RA, Michels KB, Moysich KB, Bernstein L, Attfield KR, Gray S | title = Environmental pollutants, diet, physical activity, body size, and breast cancer: where do we stand in research to identify opportunities for prevention? | journal = Cancer | volume = 109 | issue = 12 Suppl | pages = 2627–34 | date = June 2007 | pmid = 17503444 | doi = 10.1002/cncr.22656 }}</ref> Although the radiation from [[mammography]] is a low dose, it is estimated that yearly screening from 40 to 80 years of age will cause approximately 225 cases of fatal breast cancer per million women screened.<ref>{{cite journal | vauthors = Hendrick RE | title = Radiation doses and cancer risks from breast imaging studies | journal = Radiology | volume = 257 | issue = 1 | pages = 246–53 | date = October 2010 | pmid = 20736332 | doi = 10.1148/radiol.10100570 | doi-access = free }}</ref>