Cancer Prevention: An Overview

The simple versionExplain▾

Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases is lowered, which can reduce the burden of cancer and lower the number of deaths from it.

Cancer is not a single disease but a group of related diseases. Many things in our genes, our lifestyle, and the environment around us may increase or decrease our risk of getting cancer.

Scientists study many ways to help prevent cancer, including 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 formsExplain▾

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, and each cell contains genes that guide how the body grows, develops, and repairs itself.

Changes, called 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. 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 changeExplain▾

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, but 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, which lower the body's ability to keep cancer from forming.

Other factors, such as diet, alcohol, physical activity, obesity, and diabetes, may affect cancer risk. 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 riskExplain▾

• Chemoprevention. For people at high risk, some medicines can lower cancer risk. For example, certain medicines have been shown to lower the risk of breast cancer in high-risk women, and 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. People with certain gene changes or a strong personal or family history 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 riskExplain▾

• Aspirin has not been shown to prevent most cancers, though 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.