Older age is the main risk factor for cancer. This largely reflects cell DNA damage accumulating over time. Damage can result from biological processes or from exposure to risk factors.
This page covers other factors with the best evidence of an association with cancer risk; this list is not exhaustive.
See our other pages for general information about cancer, or ways to reduce your risk.
View our latest cancer statistics including key stats, in-depth explanations and raw data on cancer incidence, mortality, survival, risk, and diagnosis and treatment.
View full A-Z cancer statisticsSee information and explanations on terminology used for statistics and reporting of cancer, and the methods used to calculate some of our statistics.
Go to local cancer statistics - search profiles by area, constituency or health board in the UK.
Go to devolved nations overview for an overview of Wales, Scotland or Northern Ireland.
You are welcome to reuse this Cancer Research UK content for your own work. Credit us as authors by referencing Cancer Research UK as the primary source. Suggested styles are:
Web content: Cancer Research UK, full URL of the page, Accessed [month] [year].
Publications: Cancer Research UK ([year of publication]), Name of publication, Cancer Research UK.
Graphics (when reused unaltered): Credit: Cancer Research UK.
Graphics (when recreated with differences): Based on a graphic created by Cancer Research UK.
When Cancer Research UK material is used for commercial reasons, we encourage a donation to our life-saving research. Send a cheque payable to Cancer Research UK to: Cancer Research UK, 2 Redman Place, London, E20 1JQ.
Donate onlineStay up to date by signing up to our cancer statistics and intelligence newsletter.
We are grateful to the many organisations across the UK which collect, analyse, and share the data which we use, and to the patients and public who consent for their data to be used.
Find out more about the sources which are essential for our statistics
Lifetime risk estimates calculated by the Cancer Intelligence Team at Cancer Research UK 2023.
Sasieni PD, Shelton J, Ormiston-Smith N, et al. What is the lifetime risk of developing cancer?: The effect of adjusting for multiple primaries Br J Cancer, 2011.105(3): p.460-5.
Brown KF, Rumgay H, Dunlop C, et al. The fraction of cancer attributable to known risk factors in England, Wales, Scotland, Northern Ireland, and the UK overall in 2015. British Journal of Cancer.
Endogenous Hormones Breast Cancer Collaborative Group. Circulating sex hormones and breast cancer risk factors in postmenopausal women: reanalysis of 13 studies. Br J Cancer 2011;105 (5):709-22.
Walker K, Bratton DJ, Frost C. Premenopausal endogenous oestrogen levels and breast cancer risk: a meta-analysis. Br J Cancer 2011;105(9):1451-57.
Kaaks R, Tikk K, Sookthai D, et al. Premenopausal serum sex hormone levels in relation to breast cancer risk, overall and by hormone receptor status-Results from the EPIC cohort. Int J Cancer 2013;doi: 10.1002/ijc.28528.
Pettersson A, Graff RE, Ursin G, et al. Mammographic density phenotypes and risk of breast cancer: a meta-analysis. J Natl Cancer Inst 2014;106(5).
McCormack VA, dos Santos Silva I. Breast Density and Parenchymal Patterns as Markers of Breast Cancer Risk: A Meta- analysis. Cancer Epidem Biomar Prev 2006;15(6):1159-69.
Bertrand KA, Tamimi RM, Scott CG, et al. Mammographic density and risk of breast cancer by age and tumor characteristics. Breast Cancer Res 2013;15(6):R104.
Boyd NF, Dite GS, Stone J, et al. Heritability of Mammographic Density, a Risk Factor for Breast Cancer. New Engl J Med 2002;347(12):886-94.
Ursin G, Lillie EO, Lee E, et al. The Relative Importance of Genetics and Environment on Mammographic Density. Cancer Epidem Biomar Prev 2009;18(1):102-12.
Tamimi RM, Byrne C, Colditz GA, et al. Endogenous Hormone Levels, Mammographic Density, and Subsequent Risk of Breast Cancer in Postmenopausal Women. J Natl Cancer Inst 2007;99(15):1178-87.
Varghese JS, Smith PL, Folkerd E, et al. The Heritability of Mammographic Breast Density and Circulating Sex-Hormone Levels: Two Independent Breast Cancer Risk Factors. Cancer Epidem Biomar Prev 2012;21(12):2167-75.
Schoemaker MJ, Folkerd EJ, Jones ME, et al. Combined effects of endogenous sex hormone levels and mammographic density on postmenopausal breast cancer risk: results from the Breakthrough Generations Study. Br J Cancer. 2014 Apr 1;110(7):1898-907.
Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50 302 women with breast cancer and 96 973 women without the disease. Lancet 2002;360(9328):187-95.
Ma H, Bernstein L, Pike MC, et al. Reproductive factors and breast cancer risk according to joint estrogen and progesterone receptor status: a meta-analysis of epidemiological studies. Breast Cancer Res 2006;8:R43.
Ritte R, Tikk K, Lukanova A, et al. Reproductive factors and risk of hormone receptor positive and negative breast cancer: a cohort study. BMC Cancer. 2013 Dec 9;13:584.
Lambertini M, Santoro L, Del Mastro L, et al. Reproductive behaviors and risk of developing breast cancer according to tumor subtype: A systematic review and meta-analysis of epidemiological studies. Cancer Treat Rev. 2016 Sep;49:65-76.
Pan H, He Z, Ling L, et al. Reproductive factors and breast cancer risk among BRCA1 or BRCA2 mutation carriers: Results from ten studies Cancer Epidemiol. 2014 Feb;38(1):1-8.
Friebel TM, Domchek SM, Rebbeck TR. Modifiers of cancer risk in BRCA1 and BRCA2 mutation carriers: systematic review and meta-analysis. J Natl Cancer Inst 2014;106(6):dju091.
Collaborative Group on Hormonal Factors in Breast Cancer. Menarche, menopause, and breast cancer risk: individual participant meta-analysis, including 118 964 women with breast cancer from 117 epidemiological studies. Lancet Oncol 2012;13(11):1141-51.
Bodicoat DH, Schoemaker MJ, Jones ME, et al. Timing of pubertal stages and breast cancer risk: the Breakthrough Generations Study. Breast Cancer Res. 2014 Feb 4;16(1):R18.
Bodicoat DH, Schoemaker MJ, Jones ME, et al. Timing of pubertal stages and breast cancer risk: the Breakthrough Generations Study. Breast Cancer Res. 2014 Feb 4;16(1):R18.
Nichols HB, Trentham-Dietz A, Newcomb PA, et al. Postoophorectomy estrogen use and breast cancer risk. Obstet Gynecol. 2012 Jul;120(1):27-36.
Press DJ, Sullivan-Halley J, Ursin G, et al. Breast cancer risk and ovariectomy, hysterectomy, and tubal sterilization in the women's contraceptive and reproductive experiences study. Am J Epidemiol. 2011 Jan 1;173(1):38-47.
Kim H, Woo O, Park K, et al. The relationship between twin births and maternal risk of breast cancer: a meta-analysis. Breast Cancer Res Treat 2012;131(2):671-77.
Reeves GK, Pirie K, Green J, et al. Reproductive factors and specific histological types of breast cancer: prospective study and meta-analysis. Br J Cancer 2009;100(3):538-44.
International Agency for Research on Cancer. List of Classifications by cancer sites with sufficient or limited evidence in humans, Volumes 1 to 118. Accessed June 2017.
Brown KF, Rumgay H, Dunlop C, et al. The fraction of cancer attributable to known risk factors in England, Wales, Scotland, Northern Ireland, and the UK overall in 2015. British Journal of Cancer.
Wu L, Zhu J. Linear reduction in thyroid cancer risk by oral contraceptive use: a dose–response meta-analysis of prospective cohort studies. Human Reproduction 2015;30(9):2234-2240.
Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and hormonal contraceptives: collaborative reanalysis of individual data on 53 297 women with breast cancer and 100 239 women without breast cancer from 54 epidemiological studies. The Lancet 1996;347(9017):1713 -27.
Gierisch JM, Coeytaux RR, Urrutia RP, et al. Oral Contraceptive Use and Risk of Breast, Cervical, Colorectal, and Endometrial Cancers: A Systematic Review. Cancer Epidemiology Biomarkers Prev. 2013;[Epub ahead of print]
Samson M, Porter N, Orekoya O, et al. Progestin and breast cancer risk: a systematic review. Breast Cancer Research and Treatment 2015;155(1):3-12.
Moorman PG, Havrilesky LJ, et al. Oral contraceptives and risk of ovarian cancer and breast cancer among high-risk women: a systematic review and meta-analysis. J Clin Oncol 2013;31 (33):4188-98.
Brown KF, Rumgay H, Dunlop C, et al. The fraction of cancer attributable to known risk factors in England, Wales, Scotland, Northern Ireland, and the UK overall in 2015 British Journal of Cancer 2018.
Collaborative Group on Hormonal Factors in Breast Cancer. Type and timing of menopausal hormone therapy and breast cancer risk: individual participant meta-analysis of the worldwide epidemiological evidence. The Lancet 2019;394(10204):1159-1168.
Million Women Study Collaborators. Breast cancer and hormone-replacement therapy in the Million Women Study. Lancet 2003;362(9382):419-27.
Tempfer CB, Froese G, Heinze G, et al. Side effects of phytoestrogens: a meta-analysis of randomized trials. Am J Med. 2009 Oct;122(10):939-46.e9.
Lethaby A, Marjoribanks J, Kronenberg F, et al. Phytoestrogens for menopausal vasomotor symptoms. Cochrane Database Syst Rev. 2013 Dec 10;12:CD001395.
Lichtenstein P, Holm NV, Verkasalo PK, et al. Environmental and Heritable Factors in the Causation of Cancer — Analyses of Cohorts of Twins from Sweden, Denmark, and Finland. New Engl J Med 2000;343(2):78-85.
Zöller B, Li X, Sundquist J, Sundquist K. Familial transmission of prostate, breast and colorectal cancer in adoptees is related to cancer in biological but not in adoptive parents: a nationwide family study. Eur J Cancer 2014;50(13):2319-27.
Lee M, Czene K, Rebora P, et al. Patterns of changing cancer risks with time since diagnosis of a sibling. Int J Cancer 2015 April 15:136(8):1948-56.
Collaborative Group on Hormonal Factors in Breast Cancer. Familial breast cancer: collaborative reanalysis of individual data from 52 epidemiological studies including 58 209 women with breast cancer and 101 986 women without the disease. Lancet 2001;358 (9291):1389-99.
Pharoah PD, Day NE, Duffy S, et al. Family history and the risk of breast cancer: A systematic review and meta- analysis. Int J Cancer 1997;71(5):800-09.
Mavaddat N, Pharoah P, Blows F, et al. Familial relative risks for breast cancer by pathological subtype: a population-based cohort study. Breast Cancer Res 2010;12(1):R10.
Antoniou A, Pharoah PDP, Narod S, et al. Average Risks of Breast and Ovarian Cancer Associated with BRCA1 or BRCA2 Mutations Detected in Case Series Unselected for Family History: A Combined Analysis of 22 Studies. Am J Hum Genet 2003;72(5):1117-30.
Evans DGR, Ingham SL, Buchan I, et al. Increased Rate of Phenocopies in All Age Groups in BRCA1/BRCA2 Mutation Kindred, but Increased Prospective Breast Cancer Risk Is Confined to BRCA2 Mutation Carriers. Cancer Epidem Biomar Prev 2013;22(12):2269-76.
Widschwendter M, Rosenthal AN, Philpott S, et al. The sex hormone system in carriers of BRCA1/2 mutations: a case-control study. Lancet Oncol. 2013;14(12):1226-32.
Metcalfe K, Lubinski J, Lynch HT, et al. Family history of cancer and cancer risks in women with BRCA1 or BRCA2 mutations. J Natl Cancer Inst 2010;102(24):1874-8.
Narod SA, Tung N, Lubinski J, et al. A prior diagnosis of breast cancer is a risk factor for breast cancer in BRCA1 and BRCA2 carriers. Curr Oncol 2014;21(2):64-8.
Tea MK, Kroiss R, Muhr D, et al. Central European BRCA2 mutation carriers: Birth cohort status correlates with onset of breast cancer. Maturitas 2013;77(1):68-72.
Turnbull C, Rahman N. Genetic Predisposition to Breast Cancer: Past, Present, and Future. Ann Rev Genom Hum Genet 2008;9(1):321-45.
Easton DF. How many more breast cancer predisposition genes are there? Breast Cancer Res 1999;1(1):14 - 17.
Peto J, Collins N, Barfoot R, et al. Prevalence of BRCA1 and BRCA2 Gene Mutations in Patients With Early-Onset Breast Cancer. J Natl Cancer Inst 1999;91(11):943- 49.
Ford D, Easton DF, Stratton M, et al. Genetic Heterogeneity and Penetrance Analysis of the BRCA1 and BRCA2 Genes in Breast Cancer Families. Am J Hum Genet 1998;62(3):676-89.
Lauby-Secretan B, Scoccianti C, Loomis D, et al. Body Fatness and Cancer--Viewpoint of the IARC Working Group. N Engl J Med. 2016 Aug 25;375(8):794-8.
World Cancer Research Fund / American Institute for Cancer Research. Continuous Update Project Findings & Reports. Accessed June 2017.
Endogenous Hormones Breast Cancer Collaborative Group. Body Mass Index, Serum Sex Hormones, and Breast Cancer Risk in Postmenopausal Women. J Natl Cancer Inst 2003;95(16):1218-26.
Vrieling A, Buck K, Kaaks R, et al. Adult weight gain in relation to breast cancer risk by estrogen and progesterone receptor status: a meta-analysis. Breast Cancer Res Treat 2010;123 (3):641-49.
Kyrgiou M, Kalliala I, Markozannes G, et al. Adiposity and cancer at major anatomical sites: umbrella review of the literature. BMJ 2017;:j477.
Cheraghi Z, Poorolajal J, Hashem T, et al. Effect of Body Mass Index on Breast Cancer during Premenopausal and Postmenopausal Periods: A Meta-Analysis. PLoS ONE 2012;7(12):e51446.
Munsell MF, Sprague BL, Berry DA, et al. Body mass index and breast cancer risk according to postmenopausal estrogen-progestin use and hormone receptor status. Epidemiol Rev. 2014;36(1):114-36.
Suzuki R, Orsini N, Saji S, et al. Body weight and incidence of breast cancer defined by estrogen and progesterone receptor status—A meta-analysis. Int J Cancer 2009;124(3):698-712.
Harvie M, Hooper L, Howell AH. Central obesity and breast cancer risk: a systematic review. Obes Rev 2003;4 (3):157-73.
Gaudet MM, Carter BD, Patel AV, et al. Waist circumference, body mass index, and postmenopausal breast cancer incidence in the Cancer Prevention Study-II Nutrition Cohort. Cancer Causes Control. 2014;25(6):737-45.
Yang XR, Chang-Claude J, Goode EL, et al. Associations of Breast Cancer Risk Factors With Tumor Subtypes: A Pooled Analysis From the Breast Cancer Association Consortium Studies. J Natl Cancer Inst 2011;103(3):250-63.
Amadou A, Ferrari P, Muwonge R, et al. Overweight, obesity and risk of premenopausal breast cancer according to ethnicity: a systematic review and dose-response meta-analysis. Obes Rev 2013;14(8):665-78.
Kawai M, Malone KE, Tang MT, et al. Height, body mass index (BMI), BMI change, and the risk of estrogen receptor-positive, HER2-positive, and triple-negative breast cancer among women ages 20 to 44 years. Cancer. 2014 Feb 5.
Emaus MJ, van Gils CH, Bakker MF, et al. Weight change in middle adulthood and breast cancer risk in the EPIC-PANACEA study. Int J Cancer 2014.
Xue F, Michels KB. Intrauterine factors and risk of breast cancer: a systematic review and meta-analysis of current evidence. Lancet Oncol 2007;8(12):1088-100.
Park S, Kang D, McGlynn K, et al. Intrauterine environments and breast cancer risk: meta- analysis and systematic review. Breast Cancer Res 2008;10(1):R8.
Michels KB, Xue F. Role of birthweight in the etiology of breast cancer. Int J Cancer 2006;119 (9):2007-25.
Hajiebrahimi M, Bahmanyar S, Oberg S, et al. Breast cancer risk in opposite-sexed twins: influence of birth weight and co-twin birth weight. J Natl Cancer Inst. 2013;105(23):1833-6.
Robinson D, Holmberg L, Moller H. The occurrence of invasive cancers following a diagnosis of breast carcinoma in situ. Br J Cancer 2008;99(4):611-15.
Soerjomataram I, Louwman WJ, van der Sangen MJC, et al. Increased risk of second malignancies after in situ breast carcinoma in a population-based registry. Br J Cancer 2006;95(3):393- 97.
Aebi S, Davidson T, Gruber G, et al. Primary breast cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol 2011;22(suppl 6):vi12-vi24.
Innos K, Horn-Ross P. Risk of second primary breast cancers among women with ductal carcinoma in situ of the breast. Breast Cancer Res Treat 2008;111(3):531-40.
Li CI, Malone KE, Saltzman BS, et al. Risk of invasive breast carcinoma among women diagnosed with ductal carcinoma in situ and lobular carcinoma in situ, 1988-2001. Cancer 2006;106 (10):2104-12.
Reulen RC, Frobisher C, Winter DL, et al. Long-term risks of subsequent primary neoplasms among survivors of childhood cancer. JAMA 2011;305(22):2311-19.
Berrington de Gonzalez A, Curtis RE, Gilbert E, et al. Second solid cancers after radiotherapy for breast cancer in SEER cancer registries. Br J Cancer 2009;102(1):220-26.
Neta G, Anderson W, Gilbert E, et al. Variation in the risk of radiation-related contralateral breast cancer by histology and estrogen receptor expression in SEER. Breast Cancer Res Treat 2012;131(3):1021-27.
Maddams J, Parkin DM, Darby SC. The cancer burden in the United Kingdom in 2007 due to radiotherapy. Int J Cancer 2011;129 (12):2885-93.
de González AB, Darby S. Risk of cancer from diagnostic X-rays: estimates for the UK and 14 other countries. Lancet 2004;363(9406):345-51.
Mathews JD, Forsythe AV, Brady Z, et al. Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. BMJ 2013;346.
Bagnardi V, Rota M, Botteri E, et al. Alcohol consumption and site-specific cancer risk: a comprehensive dose-response meta-analysis. Br J Cancer. 2015 Feb 3;112(3):580-93.
Yoon-Jung Choi, Seung-Kwon Myung, Ji-Ho Lee. Light Alcohol Drinking and Risk of Cancer: A Meta-Analysis of Cohort Studies. Cancer Research and Treatment : Official Journal of Korean Cancer Association 2018; 50(2): 474-487.
Harindra Jayasekara, Robert J. MacInnis, Robin Room. Long-Term Alcohol Consumption and Breast, Upper Aero-Digestive Tract and Colorectal Cancer Risk: A Systematic Review and Meta-Analysis. Alcohol and Alcoholism, Volume 51, Issue 3, 1 May 2016, Pages 315–330.
Rinaldi S, Peeters PHM, Bezemer ID, et al. Relationship of alcohol intake and sex steroid concentrations in blood in pre- and post-menopausal women: the European Prospective Investigation into Cancer and Nutrition. Cancer Cause Control 2006;17(8):1033-43.
Gaudet MM, Gapstur SM, Sun J, et al. Active Smoking and Breast Cancer Risk: Original Cohort Data and Meta-Analysis. J Natl Cancer Inst 2013;105(8):515-25.
Gaudet MM, Carter BD, Brinton LA, et al. Pooled analysis of active cigarette smoking and invasive breast cancer risk in 14 cohort studies. Int J Epidemiol. 2016 Dec 28. pii: dyw288.
Macacu A, Autier P, Boniol M, et al. Active and passive smoking and risk of breast cancer: a meta-analysis. Breast Cancer Res Treat. 2015 Nov;154(2):213-24.
Kawai M, Malone KE, Tang MT, et al. Active smoking and the risk of estrogen receptor-positive and triple-negative breast cancer among women ages 20 to 44 years. Cancer. 2014 Apr 1;120(7):1026-34.
Kabat GC, Kim M, Phipps AI, et al. Smoking and alcohol consumption in relation to risk of triple-negative breast cancer in a cohort of postmenopausal women. Cancer Causes Control. 2011 May;22(5):775-83.
Unar-Munguía M, Torres-Mejía G, Colchero M, et al. Breastfeeding Mode and Risk of Breast Cancer: A Dose–Response Meta-Analysis. Journal of Human Lactation 2017;33(2):422-434.
Friedenreich CM, Neilson HK, Lynch BM. State of the epidemiological evidence on physical activity and cancer prevention. Eur J Cancer 2010;46(14):2593-604.
Wu Y, Zhang D, Kang S. Physical activity and risk of breast cancer: a meta-analysis of prospective studies. Breast Cancer Res Treat 2013;137(3):869-82.
Shi Y, Li T, Wang Y, et al. Household physical activity and cancer risk: a systematic review and dose-response meta-analysis of epidemiological studies. Sci Rep. 2015. doi: 10.1038/srep14901.
