Colorectal Cancer Prevention

by National Cancer Institute

Doctors cannot always explain why one person gets cancer and another does not. However, scientists have studied general patterns of cancer in the population to learn what things around us and what things we do in our lives may increase our chance of developing cancer.

Anything that increases a person's chance of developing a disease is called a risk factor; anything that decreases a person's chance of developing a disease is called a protective factor. Some of the risk factors for cancer can be avoided, but many cannot. For example, although you can choose to quit smoking, you cannot choose which genes you have inherited from your parents. Both smoking and inheriting specific genes could be considered risk factors for certain kinds of cancer, but only smoking can be avoided. Prevention means avoiding the risk factors and increasing the protective factors that can be controlled so that the chance of developing cancer decreases.

Although many risk factors can be avoided, it is important to keep in mind that avoiding risk factors does not guarantee that you will not get cancer. Also, most people with a particular risk factor for cancer do not actually get the disease. Some people are more sensitive than others are to factors that can cause cancer. Talk to your doctor about methods of preventing cancer that might be effective for you.

The purposes of this summary on colorectal cancer prevention are to:

• Give information on colorectal cancer and how often it occurs.
• Describe colorectal cancer prevention methods.
• Give current facts about which people or groups of people would most likely be helped by following colorectal cancer prevention methods.

You can talk to your doctor or health care professional about cancer prevention methods and whether they would be likely to help you.

Colorectal Cancer Prevention

Cancer of the colon or rectum is often called colorectal cancer. The colon and the rectum are part of the large intestine, which is part of the digestive system.

Tumors found in the colon or rectum may be benign (noncancerous) growths of tissue (polyps) or malignant cancerous growths of tissue that may spread to other parts of the body.

Significance of colorectal cancer

Colorectal cancer is the second leading cause of cancer deaths in the United States. The number of new cases of colorectal cancer in the United States has been decreasing slightly, and the number of deaths due to colorectal cancer has been decreasing. The risk of colorectal cancer tends to increase after the age of 40.

Colorectal cancer prevention

Colorectal cancer can sometimes be associated with known risk factors for the disease. Many risk factors can be changed, but not all can be avoided.

Diet and Lifestyle: Diet and lifestyle may affect colorectal cancer risk. Many factors are under study.

Some studies suggest that the following may protect against colorectal cancer, but other studies have shown no preventive effect:

• A diet high in fiber and/or fruits and vegetables.
• Calcium.
• Vitamin D.
• Vitamin E.

Studies show colorectal cancer risk may be affected by the following factors:

• Folic acid: High doses of folic acid may help decrease colorectal cancer risk.
• Physical activity: A lack of physical activity, especially combined with a diet high in fat, may increase colorectal cancer risk.
• Obesity: In premenopausal women, obesity has been linked to an increased colorectal cancer risk.
• Smoking: Cigarette smoking has been linked to increased colorectal cancer risk.
• Alcohol: Drinking alcohol may increase colorectal cancer risk.

Nonsteroidal Anti-Inflammatory Drugs: Some studies have shown that the use of nonsteroidal anti-inflammatory drugs (NSAIDs) may be associated with a decreased risk of colorectal cancer. Use of NSAIDs, however, increases the risk of heart attack and stroke and of bleeding in the stomach and intestines.

Polyp Removal: Studies have shown that removing polyps, which may develop into cancer, decreases the risk of colorectal cancer. Bleeding and infection sometimes occur after polyps are removed during colonoscopy or sigmoidoscopy. Rarely, the procedure tears the colon.

Female Hormone Use: It is not known if postmenopausal hormone use affects the risk of colorectal cancer. Some studies suggest it may decrease the risk of colon cancer but not rectal cancer. Hormone use, however, may increase the risk of endometrial cancer, breast cancer, blood clots, and heart disease.

Statin Use: There is no evidence that statin use affects the risk of colorectal cancer.

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