Colorectal Cancer

Last Updated: June 1, 2003

What is colorectal cancer?
Colorectal cancer is a disease in which cells in the colon or rectum become abnormal and divide without control or order, forming a mass called a tumor. (The colon and rectum are parts of the body’s digestive system that remove nutrients from food and water and store solid waste until it passes out of the body.)

Cancer cells invade and destroy the tissue around them. They also can break away from the tumor and spread to form new tumors in other parts of the body.

Colorectal cancer is the fourth most common type of cancer and the second leading cause of cancer death in the United States. The number of new cases and deaths resulting from this disease is decreasing. Still, over 135,000 new cases are diagnosed and more than 56,000 people die from colorectal cancer each year.

Who is at risk for colorectal cancer?
The exact causes of colorectal cancer are not known. However, studies show that certain factors increase a person’s chance of developing colorectal cancer:

Age – Colorectal cancer is more likely to occur as people get older. Although the disease can occur at any age, most people who develop colorectal cancer are over the age of 50.

Polyps – Polyps are benign (noncancerous) growths that protrude from the inner wall of the colon or rectum. They are relatively common in people over age 50. Because experts believe most colorectal cancers develop in polyps, detecting and removing these growths may be a way to help prevent colorectal cancer. The procedure to remove polyps is called a polypectomy.

Familial adenomatous polyposis, or FAP, is a rare, inherited condition in which hundreds of polyps develop in the colon and rectum. Because this condition is extremely likely to lead to colorectal cancer, it is often treated with surgery to remove the colon and rectum (colectomy). Rectum-sparing surgery may be an option. Researchers are studying the use of anti-inflammatory drugs as a treatment for FAP.

Personal history – A person who has already had colorectal cancer may develop colorectal cancer a second time. Also, research studies show that women with a history of ovarian, uterine or breast cancer have a higher-than-average chance of developing colorectal cancer.

Family history – Close relatives (parents, siblings or children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the family member developed the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.

Ulcerative colitis or Crohn’s colitis – Ulcerative colitis is a condition that causes inflammation and sores (ulcers) in the lining of the colon. Crohn’s colitis (also called Crohn’s disease) causes chronic inflammation of the gastrointestinal tract, most often the small intestine (the part of the digestive tract that is located between the stomach and the large intestine). People who have ulcerative colitis or Crohn’s colitis may be more likely to develop colorectal cancer than people who do not have these conditions.

Diet – Some evidence suggests that the development of colorectal cancer may be associated with a diet that is high in fat and calories and low in foods with fiber, such as whole grains, fruits, and vegetables. Researchers are exploring what role these and other dietary components play in the development of colorectal cancer.

Source: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

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