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Colon Cancer

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Also known as: Colorectal Cancer

What is colon cancer?

Diagram showing position of colonThe colon is five feet long and makes up the majority of the large intestine. In the path that food takes through the body (alimentary canal), the colon follows the small intestine and comes before the rectum. The colon is responsible for absorbing water, vitamins, and minerals from the intestinal contents and conserving them. It also mixes the intestinal contents, forms stools, and rids the body of undigested material.

Colon and rectum cancers are sometimes referred to together as "colorectal cancer;" in this article, they will be referred to as "colon cancer." Together they are the third most common cancer in adults and the second leading cause of cancer deaths in men and women in the United States. According to the American Cancer Society, an estimated 101, 340 cases of colon cancer and 39, 870 cases of rectal cancer will be diagnosed in the U.S. in 2011 and as many as 49, 380 people will die of colorectal cancer.

There are glands in the colon that produce mucus and lubricate the lining of the colon and rectum. About 95% of colorectal cancers are adenocarcinomas; they start in the cells that form these glands. Most cases of colon cancer begin with the development of benign polyps, finger-like growths that protrude into the intestinal cavity. These polyps are relatively common in people over age 50, and most remain benign. Some, however, can become cancerous, with the ability to invade colon tissues and to spread to other parts of the body (metastasize). The tumors they form can create blockages in the intestine, preventing elimination.

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