--- topic: "Cancer Prevention" title: "How to Lower Your Cancer Risk" order: 1 description: "About four in ten US cancers are linked to changeable factors. What the evidence says about tobacco, weight, alcohol, food, sun, vaccines and screening." question: "What can you do to lower your risk of cancer?" answer: "About 40 percent of US cancers are linked to changeable factors, mainly smoking, weight and alcohol, so avoiding tobacco and getting screened probably lowers risk." actions: - "Stay tobacco-free: smoking causes about 19 percent of US cancers and 29 percent of cancer deaths, and quitting before 40 cuts the added death risk by about 90 percent [1][8]." - "Keep a healthy weight and move: the American Cancer Society advises 150 to 300 weekly minutes of moderate activity; active people had lower risk of 13 of 26 cancers [2][10]." - "Get the HPV vaccine (ideally before 17), use sun protection, and ask when to start colorectal screening, recommended from age 45 in the US [4][5][6]." cautions: - "Do not take supplements to prevent cancer: vitamin E raised prostate cancer risk by 17 percent in a trial of 35,533 men, and WCRF/AICR advises against them [7][3]." - "New lumps, unexplained bleeding or weight loss, trouble swallowing, or a cough with other unexplained symptoms need a doctor, not a diet change: see [when to see a doctor](/when-to-see-a-doctor/when-home-remedies-are-not-enough) [12]." - "If you have had cancer or are in treatment, ask your oncology team before changing your diet or adding supplements; this page is about prevention, not treatment." confidence: 4 confidenceNote: "Registry data, pooled cohorts, vaccine and supplement trials, and consistent guidelines agree, but most diet and activity links are observational and attribution figures are modeled estimates." evidenceSummary: rctCount: 2 observationalCount: 4 metaAnalysisCount: 1 totalParticipants: "1.4 million+ in pooled activity cohorts" replicated: true newestStudyYear: 2026 references: - id: "1" pmid: "38990124" title: "Proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors in the United States, 2019" authors: "Islami F, Marlow EC, Thomson B, et al." year: 2024 journal: "CA Cancer J Clin" - id: "2" pmid: "32515498" title: "American Cancer Society guideline for diet and physical activity for cancer prevention" authors: "Rock CL, Thomson C, Gansler T, et al." year: 2020 journal: "CA Cancer J Clin" - id: "3" pmid: "31758189" title: "The World Cancer Research Fund/American Institute for Cancer Research Third Expert Report on Diet, Nutrition, Physical Activity, and Cancer: Impact and Future Directions" authors: "Clinton SK, Giovannucci EL, Hursting SD" year: 2020 journal: "J Nutr" - id: "4" pmid: "32997908" title: "HPV Vaccination and the Risk of Invasive Cervical Cancer" authors: "Lei J, Ploner A, Elfström KM, et al." year: 2020 journal: "N Engl J Med" - id: "5" pmid: "21135266" title: "Reduced melanoma after regular sunscreen use: randomized trial follow-up" authors: "Green AC, Williams GM, Logan V, et al." year: 2011 journal: "J Clin Oncol" - id: "6" pmid: "34003218" title: "Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement" authors: "Davidson KW, Barry MJ, Mangione CM, et al. (US Preventive Services Task Force)" year: 2021 journal: "JAMA" - id: "7" pmid: "21990298" title: "Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT)" authors: "Klein EA, Thompson IM Jr, Tangen CM, et al." year: 2011 journal: "JAMA" - id: "8" pmid: "23343063" title: "21st-century hazards of smoking and benefits of cessation in the United States" authors: "Jha P, Ramasundarahettige C, Landsman V, et al." year: 2013 journal: "N Engl J Med" - id: "9" pmid: "25422909" title: "Alcohol consumption and site-specific cancer risk: a comprehensive dose-response meta-analysis" authors: "Bagnardi V, Rota M, Botteri E, et al." year: 2015 journal: "Br J Cancer" - id: "10" pmid: "27183032" title: "Association of Leisure-Time Physical Activity With Risk of 26 Types of Cancer in 1.44 Million Adults" authors: "Moore SC, Lee IM, Weiderpass E, et al." year: 2016 journal: "JAMA Intern Med" - id: "11" pmid: "26514947" title: "Carcinogenicity of consumption of red and processed meat" authors: "Bouvard V, Loomis D, Guyton KZ, et al." year: 2015 journal: "Lancet Oncol" - id: "12" url: "https://www.nice.org.uk/guidance/ng12" title: "Suspected cancer: recognition and referral" authors: "National Institute for Health and Care Excellence" year: 2026 journal: "NICE guideline NG12" --- About 4 in 10 US cancers are linked to factors you can change, led by smoking, then excess weight and alcohol [1]. Diet and activity guidelines agree on the basics: keep a healthy weight, be active, eat mostly plants, and limit alcohol, red and processed meat, and highly processed foods [2][3]. Vaccination, sun protection and screening add to this [4][5][6], but supplements do not: vitamin E raised prostate cancer risk in a large trial [7]. ## How it works ### How much is preventable In 2019, an estimated 40.0 percent of new US cancers and 44.0 percent of cancer deaths in adults 30 and older were attributable to modifiable factors. Cigarette smoking led (19.3 percent of cases, 28.5 percent of deaths), followed by excess body weight (7.6 and 7.3 percent) and alcohol (5.4 and 4.1 percent). Red and processed meat, low fruit, vegetable and fiber intake, inactivity, ultraviolet light and seven infections made up the rest [1]. These are modeled estimates, not a promise about any one person. ### What the major guidelines agree on The American Cancer Society (ACS) and the World Cancer Research Fund (WCRF/AICR) recommend patterns rather than single foods [2][3]: - Keep a healthy weight and avoid weight gain in adult life. - Be active: the ACS advises 150 to 300 minutes of moderate activity, or 75 to 150 of vigorous, each week [2]. - Eat plenty of vegetables, fruit, whole grains and beans. Limit red and processed meat, sugary drinks, and highly processed foods and refined grains. - Both say it is best not to drink alcohol; if you do, the ACS caps it at one drink a day for women and two for men [2][3]. See [alcohol and health](/alcohol/is-any-amount-of-alcohol-good-for-you). ### The numbers behind the big four - **Tobacco.** Smokers lose at least a decade of life; quitting before 40 cut the added risk of death by about 90 percent [8]. - **Alcohol.** Compared with non-drinkers and occasional drinkers, heavy drinkers had about five times the risk of oral, throat and oesophageal squamous cell cancers, 1.6 times the risk of breast cancer and 1.4 times that of colorectal cancer [9]. - **Activity.** More leisure-time activity went with lower risk of 13 of 26 cancers, including lung, liver, kidney, colon and breast [10]. - **Meat.** The International Agency for Research on Cancer classed processed meat as carcinogenic to humans and red meat as probably carcinogenic. The label reflects how sure the evidence is, not how big the risk is [11]. ### Vaccines, sun and screening - **HPV vaccine.** Among 1.67 million Swedish girls and women, invasive cervical cancer was about 88 percent less common in those vaccinated before 17 [4]. - **Sun.** In a trial of 1,621 adults, daily sunscreen was followed by half as many new melanomas, a borderline result, and fewer invasive ones [5]. - **Screening.** Colorectal screening is recommended for adults 45 to 75, and for some 76 to 85 [6]. ### Supplements and symptoms Supplements do not replace food: in SELECT, vitamin E raised prostate cancer risk by 17 percent, and WCRF/AICR advises against supplements for prevention [7][3]. And prevention is no substitute for checking symptoms: unexplained lumps, bleeding, weight loss or trouble swallowing deserve a visit [12]. ## The evidence in detail ### Attribution and guidelines Islami and colleagues combined national cancer and death counts, national surveys of risk-factor prevalence and relative risks from large published pooled analyses. For 2019 they attributed 713,340 of 1,781,649 cancers (40.0 percent) and 262,120 of 595,737 deaths (44.0 percent) to the factors studied; for 19 of 30 cancer types, more than half of cases and deaths were attributable [1]. The ACS guideline and the WCRF/AICR Third Expert Report both summarize the evidence on diet, activity and weight and pair it with recommendations for communities as well as individuals [2][3]. Attribution assumes the associations are causal and reversible, which is least certain for some dietary factors. ### Alcohol and activity A dose-response meta-analysis of 572 studies (486,538 cancer cases) found that heavy drinkers, compared with non-drinkers and occasional drinkers, had relative risks of 5.13 for oral and pharyngeal cancer, 4.95 for oesophageal squamous cell carcinoma, 2.65 for laryngeal, 2.07 for liver, 1.61 for breast and 1.44 for colorectal cancer, with a clear dose-risk relationship for these. Lymphoma risk ran the other way and was lower [9]. Moore and colleagues pooled 12 cohorts (1.44 million adults, 186,932 cancers). High versus low leisure-time activity went with lower risk of 13 cancers, for example esophageal adenocarcinoma (hazard ratio 0.58), liver (0.73), lung (0.74), kidney (0.77), colon (0.84) and breast (0.90). Activity was also linked to higher melanoma (1.27) and prostate cancer (1.05) risk [10]. ### Vaccines, sun and screening In a Swedish register study of 1,672,983 girls and women aged 10 to 30, cervical cancer was diagnosed in 19 vaccinated and 538 unvaccinated women. After adjustment, the incidence rate ratio was 0.12 (95% CI 0.00 to 0.34) for vaccination before 17 and 0.47 (0.27 to 0.75) at 17 to 30 [4]. It is observational, so unmeasured differences between vaccinated and unvaccinated women remain possible. The Nambour trial randomized 1,621 Australian adults to daily or discretionary sunscreen on the head and arms until 1996. Ten years later there were 11 new primary melanomas in the daily group and 22 in the discretionary group (hazard ratio 0.50, 0.24 to 1.02, P=0.051), and 3 versus 11 invasive melanomas (0.27, 0.08 to 0.97) [5]. The US Preventive Services Task Force concluded with high certainty that colorectal screening at 50 to 75 has substantial net benefit, with moderate certainty of moderate benefit at 45 to 49 and small benefit at 76 to 85 [6]. ### Null and harmful results The Selenium and Vitamin E Cancer Prevention Trial randomized 35,533 men (34,887 analyzed) to selenium, vitamin E 400 IU a day, both, or placebo. With extra follow-up, prostate cancer occurred in 620 men on vitamin E versus 529 on placebo (hazard ratio 1.17, 99% CI 1.004 to 1.36); selenium (1.09) and the combination (1.05) were not significantly different from placebo [7]. That is one cancer site and one supplement, but the WCRF/AICR recommendations advise against supplements for cancer prevention [3]. ### Where the evidence is weaker Most diet and activity links come from observational studies, which cannot fully separate one habit from another. Attribution percentages rest on assumptions. Alcohol and lymphoma, and activity and melanoma, went the opposite way from the general pattern, and the Nambour melanoma result only just missed conventional significance [5][9][10]. Screening benefit shrinks with age [6]. ### Bottom line Confidence is fairly high (4 of 5). Smoking, weight, alcohol, activity, HPV vaccination and screening have strong, consistent support [1][4][6][9][10], while claims about individual foods are weaker and supplements have not shown protection [7]. Prevention lowers risk and never guarantees against cancer, so symptoms still need a doctor [12].