Preventing Cancer

Factors That are Known to Increase the Risk of Cancer

Cigarette Smoking and Tobacco Use

Tobacco use is strongly linked to an increased risk for many kinds of cancer. Smoking cigarettes is the leading cause of the following types of cancer:

• Acute myelogenous leukemia (AML)
• Bladder cancer
• Cervical cancer
• Esophageal cancer
• Kidney cancer
• Lung cancer
• Oral cavity cancer
• Pancreatic cancer
• Stomach cancer

Not smoking or quitting smoking lowers the risk of getting cancer and dying from cancer. Scientists believe that cigarette smoking causes about 30% of all cancer deaths in the United States.

See the following National Cancer Institute PDQ summaries for more information:

• Lung Cancer Prevention
• Prevention and Cessation of Cigarette Smoking: Control of Tobacco Use

Infections

Certain viruses and bacteria may be able to cause cancer. Viruses and other infection-causing agents cause more cases of cancer in the developing world (about 1 in 4 cases of cancer) than in developed nations (less than 1 in 10 cases of cancer). Examples of cancer-causing viruses and bacteria include:

• Human papillomavirus (HPV) increases the risk for cancers of the cervix, penis, vagina, anus, and oropharynx.
• Hepatitis B and hepatitis C viruses increase the risk for liver cancer.
• Epstein-Barr virus increases the risk for Burkitt lymphoma.
• Helicobacter pylori increases the risk for gastric cancer.

Two vaccines prevent infection by cancer-causing agents have already been developed and approved by the U.S. Food and Drug Administration (FDA). One is a vaccine to prevent infection with hepatitis B virus. The other protects against infection with strains of human papillomavirus (HPV) that cause cervical cancer. Scientists continue to work on vaccines against infections that cause cancer.

See the following National Cancer Institute PDQ summaries for more information:

• Cervical Cancer Prevention
• Liver (Hepatocellular) Cancer Prevention
• Stomach (Gastric) Cancer Prevention
• Oral Cancer Prevention

Radiation

Being exposed to radiation is a known cause of cancer. There are two main types of radiation linked with an increased risk for cancer:

• Ultraviolet radiation from sunlight: This is the main cause of nonmelanoma skin cancers.
• Ionizing radiation from medical x-rays and radon gas in our homes: Scientists believe that ionizing radiation causes leukemia, thyroid cancer, and breast cancer in women. Ionizing radiation may also be linked to myeloma and cancers of the lung, stomach, colon, esophagus, bladder, and ovary. Being exposed to radiation from diagnostic x-rays increases the risk of cancer in patients and x-ray technicians. 

See the following National Cancer Institute PDQ summaries for more information:

• Breast Cancer Prevention
• Skin Cancer Prevention 

Factors That May Affect the Risk of Cancer

Diet

The foods that you eat on a regular basis make up your diet. Diet is being studied as a risk factor for cancer. It is hard to study the effects of diet on cancer because a person’s diet includes foods that may protect against cancer and foods that may increase the risk of cancer.

It is also hard for people who take part in the studies to keep track of what they eat over a long period of time. This may explain why studies have different results about how diet affects the risk of cancer.

Some studies show that fruits and nonstarchy vegetables may protect against cancers of the mouth, esophagus, and stomach. Fruits may also protect against lung cancer.

Some studies have shown that a diet high in fat, proteins, calories, and red meat increases the risk of colorectal cancer, but other studies have not shown this.

It is not known if a diet low in fat and high in fiber, fruits, and vegetables lowers the risk of colorectal cancer.  See the American Institute for Cancer Research for more information about foods that prevent cancer.

See the following PDQ summaries for more information:

• Breast Cancer Prevention
• Colorectal Cancer Prevention

Alcohol

Studies have shown that drinking alcohol is linked to an increased risk of the following types of cancers:

• Oral cancer
• Esophageal cancer
• Breast cancer
• Colorectal cancer (in men)

Drinking alcohol may also increase the risk of liver cancer and female colorectal cancer.

See the following National Cancer Institute PDQ summaries for more information:

• Breast Cancer Prevention
• Colorectal Cancer Prevention
• Esophageal Cancer Prevention
• Oral Cancer Prevention
• Liver (Hepatocellular) Cancer Prevention

Physical Activity

Studies show that people who are physically active have a lower risk of certain cancers than those who are not. It is not known if physical activity itself is the reason for this.

Studies show a strong link between physical activity and a lower risk of colorectal cancer. Some studies show that physical activity protects against postmenopausal breast cancer and endometrial cancer.

See the following National Cancer Institute PDQ summaries for more information:

• Breast Cancer Prevention
• Colorectal Cancer Prevention
• Endometrial Cancer Prevention

Obesity

Studies show that obesity is linked to a higher risk of the following types of cancer:

• Postmenopausal breast cancer
• Colorectal cancer
• Endometrial cancer
• Esophageal cancer
• Kidney cancer
• Pancreatic cancer

Some studies show that obesity is also a risk factor for cancer of the gallbladder.

Studies do not show that losing weight lowers the risk of cancers that have been linked to obesity.

See the following National Cancer Institute PDQ summaries for more information:

• Breast Cancer Prevention
• Colorectal Cancer Prevention
• Endometrial Cancer Prevention
• Lung Cancer Prevention

Information provided the National Cancer Institute.