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Digestive System

Polyp

Polyp

Colon wall

Colon Polyp

A polyp is a mushroom-shaped growth of tissue in the inner lining of the wall of the colon.The most common type of polyp, called an adenomatous polyp (shown here), is noncancerous, but it can grow and become cancerous.

Colon wall

Colon Polyp

A polyp is a mushroom-shaped growth of tissue in the inner lining of the wall of the colon.The most common type of polyp, called an adenomatous polyp (shown here), is noncancerous, but it can grow and become cancerous.

Colorectal Cancer

Cancer of the colon and cancer of the rectum are two of the most common forms of cancer. The term "colorectal cancer" is often used to describe them. Colorec-tal cancer is the third most common type of cancer among men and also is the third leading cause of cancer death among men. But the rate of cure is high—up to 90 percent—when the disease is detected and treated early.

Nearly all cases of colorectal cancer arise from previously benign (noncancerous) adenomatous polyps. The risk of colorectal cancer increases with age (occurring most often after age 50) and may be higher among people who eat a high-fat, low-fiber diet. People with ulcerative colitis (see page 269) are more likely to develop colon cancer. Colorectal cancer can run in families: if you have a parent, sibling, or child who was diagnosed with colon cancer, your risk of developing colon cancer is greater than normal.

A doctor can detect cancers just inside the rectum during a digital rectal examination. Doctors recommend an annual digital rectal examination for all men 40 and older. The most common screening test to detect colon cancer is the fecal occult blood test, which checks for traces of blood in samples of stool. Doctors recommend that all men over age 50 have a fecal occult blood test every year.

A more accurate test, recommended every 5 years, is called a flexible sigmoidoscopy, a visual examination of the lower third of the colon and rectum that uses a probe with a light and a camera attached. The doctor inserts the instrument into the colon and looks through the viewing tube to check for polyps or signs of cancer. A colonoscopy is a similar procedure, but it examines the entire length of the colon. The doctor performing a sigmoidoscopy or colonoscopy may remove tissue for a biopsy during the test.

An alternative to these procedures is a barium enema. During this test, contrast medium (a dye) is inserted through the rectum into the colon, and X rays are taken of the colon to look for abnormalities. If a suspicious area is detected in the colon during a barium enema, the doctor will order a biopsy (microscopic examination of a small piece of tissue that has been removed from the colon) to confirm the diagnosis of cancer.

A tumor in the colon is classified by stages, according to whether it has affected only the top layer of the intestinal lining, penetrated farther down into the lining, involved the surrounding lymph nodes (part of the body's immune system that fights infection), or spread to other parts of the body.

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