Colon Cancer

Definition

Colon, or colorectal, cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon).

Other types of cancer can affect the colon, such as lymphoma, carcinoid tumors, melanoma, and sarcomas. These are rare. In this article, use of the term "colon cancer" refers to colon carcinoma only.

Alternative Names

Colorectal cancer; Cancer - colon; Rectal cancer; Cancer-rectum; Adenocarcinoma- colon; Colon -adenocarcinoma

Causes, incidence, and risk factors

According to the American Cancer Society, colorectal cancer is one of the leading causes of cancer-related deaths in the United States. However, early diagnosis often leads to a complete cure.

Almost all colon cancer starts in glands in the lining of the colon and rectum. When most people and when doctors talk about colorectal cancer, this is generally what they are referring to.

There is no single cause for colon cancer. Nearly all colon cancers begin as noncancerous (benign) polyps, which slowly develop into cancer.

You have a higher risk for colon cancer if you:

• Are older than 60
• Are African American and eastern European descent
• Eat a diet high in red or processed meat
• Have cancer elsewhere in the body
• Have colorectal polyps
• Have inflammatory bowel disease (Crohn's disease or ulcerative colitis)
• Have a family history of colon cancer
• Have a personal history of breast cancer

Certain genetic syndromes also increase the risk of developing colon cancer. Two of the most common are hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, and familial adenomatous polyposis (FAP).

What you eat may play a role in your risk of colon cancer. Colon cancer may be associated with a high-fat, low-fiber diet and red meat. However, some studies found that the risk does not drop if you switch to a high-fiber diet, so the cause of the link is not yet clear.

Smoking cigarettes and drinking alcohol are other risk factors for colorectal cancer.

Symptoms

Many cases of colon cancer have no symptoms. The following symptoms, however, may indicate colon cancer:

• Abdominal pain and tenderness in the lower abdomen
• Blood in the stool
• Diarrhea, constipation, or other change in bowel habits
• Intestinal obstruction
• Narrow stools
• Unexplained anemia
• Weight loss with no known reason

Content
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Reviewer Info: David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc., and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital.; ADAM Health Illustrated Encyclopedia, 11/05/2009

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.