The short answer
Cancer prevention is action taken to lower the chance of getting cancer. Some risk factors, like smoking, can be avoided, while others, like inheriting certain genes, cannot. Ways to help prevent cancer include avoiding known causes, healthy lifestyle changes, finding precancerous conditions early, and, for some people, medicines or surgery.
Cancer prevention is action taken to lower the chance of getting cancer.
Cancer forms through a process called carcinogenesis, when changes in genes let cells grow out of control.
Some risk factors can be avoided, such as smoking; others cannot, such as inheriting certain genes.
Known causes of cancer include tobacco use, certain infections, radiation, and immunosuppressive medicines.
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The full explanation.
The simple version
Cancer prevention is action taken to lower the chance of getting cancer. Preventing cancer lowers the number of new cases. That can reduce the burden of cancer and lower the number of deaths from it.
Cancer is not a single disease. It is a group of related diseases. Many things in our genes, our lifestyle, and the environment around us may raise or lower our risk of getting cancer.
Scientists study many ways to help prevent cancer. These include avoiding or controlling things known to cause cancer, changing diet and lifestyle, finding precancerous conditions early, using medicines (chemoprevention), and risk-reducing surgery.
In short: prevention is about lowering your chance of getting cancer.
How cancer forms
Carcinogenesis is the series of steps that take place as a normal cell becomes a cancer cell. Cells are the smallest units of the body. Each cell contains genes that guide how the body grows, develops, and repairs itself.
Changes in genes, called mutations, can cause the normal controls in cells to break down. When this happens, cells do not die when they should. And new cells form when the body does not need them. The buildup of extra cells may form a tumor. Tumors can be benign (not cancer) or malignant (cancer). Malignant tumor cells invade nearby tissues and spread. Benign tumor cells do not.
Risk factors you can and cannot change
Anything that increases your chance of developing cancer is a risk factor. Anything that decreases it is a protective factor. Some risk factors can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some cancers. Only smoking can be avoided. Risk factors a person can control are called modifiable risk factors.
Factors known to increase cancer risk include:
- Cigarette smoking and tobacco use — strongly linked to many cancers. Not smoking, or quitting, lowers the risk.
- Infections — certain viruses and bacteria, such as HPV, hepatitis B and C, Epstein-Barr virus, and Helicobacter pylori.
- Radiation — including ultraviolet radiation from sunlight, and ionizing radiation such as medical x-rays and radon gas.
- Immunosuppressive medicines — taken after an organ transplant, they lower the body's ability to keep cancer from forming.
Other factors may affect cancer risk too, such as diet, alcohol, physical activity, obesity, and diabetes. Vaccines against hepatitis B and HPV have been developed to prevent some cancer-causing infections.
In short: some causes of cancer can be avoided, and some cannot.
Ways that can lower cancer risk
- Chemoprevention. For people at high risk, some medicines can lower cancer risk. Certain medicines have been shown to lower the risk of breast cancer in high-risk women. Finasteride has been shown to lower the risk of prostate cancer. These medicines can have side effects, so they are used carefully.
- Weight loss surgery. Studies have shown that weight loss surgery lowers the risk of cancers linked to being overweight.
- Risk-reducing surgery. Some people have certain gene changes, or a strong personal or family history. They may consider surgery to lower their risk. It is important to have a cancer risk assessment and counseling before making this decision.
Ways that have not been shown to lower risk
- Aspirin has not been shown to prevent most cancers. Long-term use may help prevent colorectal cancer in certain people. Aspirin can cause bleeding, so talk with your doctor first.
- Vitamins and dietary supplements have not been shown to prevent cancer. In one large trial, vitamin E taken alone increased the risk of prostate cancer.
New ways to prevent cancer are being studied in clinical trials. Your healthcare team is the best source of advice about lowering your own cancer risk.
Words to know
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Common questions
What is cancer prevention?
Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases is lowered. Scientists study many ways to help prevent cancer, including avoiding known causes, changing diet and lifestyle, finding precancerous conditions early, using medicines (chemoprevention), and risk-reducing surgery.
How does cancer start?
Cancer forms through a process called carcinogenesis, in which a normal cell becomes a cancer cell. Changes, or mutations, in genes can cause the normal controls in cells to break down. When this happens, cells do not die when they should and new cells form when the body does not need them. The buildup of extra cells may form a tumor.
Which risk factors are known to increase cancer risk?
Factors known to increase cancer risk include cigarette smoking and tobacco use, certain infections (such as HPV, hepatitis B and C, Epstein-Barr virus, and H. pylori), radiation, and immunosuppressive medicines taken after an organ transplant. Some risk factors can be avoided, but many cannot.
Can medicines or surgery prevent cancer?
For some people at high risk, yes. Chemoprevention uses substances to lower cancer risk; for example, certain medicines have been shown to lower the risk of breast or prostate cancer in high-risk people. Weight loss surgery lowers the risk of some cancers, and some people at high risk choose risk-reducing surgery after a cancer risk assessment and counseling.
Do vitamins and supplements prevent cancer?
There is not enough proof that taking multivitamins, single vitamins, or minerals can prevent cancer. Several, including vitamins B6, B12, E, C, D, beta carotene, folic acid, and selenium, have been studied but not shown to lower cancer risk. In one large trial, vitamin E taken alone increased the risk of prostate cancer.
Does aspirin prevent cancer?
Most studies have shown that aspirin does not prevent most cancers, though there is evidence that long-term aspirin use may help prevent colorectal cancer in certain people. Aspirin can cause bleeding, so it is important to talk with your doctor about the benefits and harms before starting long-term use.
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Last updated: 2026-08-05Next planned review: 2027-07-02
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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