Cancer affects your cells, the basic units of life. Healthy cells grow and divide in an orderly way to keep your body functioning normally. But sometimes this growth gets out of control — cells continue dividing even when new cells aren’t needed. In the colon and rectum, this exaggerated growth may cause precancerous polyps (adenomas, or adenomatous polyps) to form in the lining of your intestine. Over a long period of time — spanning up to several years — some of these polyps may become cancerous. In later stages of the disease, cancerous polyps may penetrate the colon walls and spread (metastasize) to nearby lymph nodes and other organs.Most colorectal cancers arise from adenomatous polyps—clusters of abnormal cells in the glands covering the inner wall of the colon. Over time, these abnormal growths enlarge and ultimately degenerate to become adenocarcinomas.

People with any of several conditions known as adenomatous polyposis syndromes have a greater-than-normal risk of colorectal cancer.

• In these conditions, numerous adenomatous polyps develop in the colon, ultimately leading to colon cancer.
• The cancer usually occurs before age 40 years.
• Adenomatous polyposis syndromes tend to run in families. Such cases are referred to as familial adenomatous polyposis (FAP). Celecoxib (Celebrex) has been FDA approved for FAP. After 6 months, celecoxib reduced the mean number of rectal and colon polyps by 28% compared to placebo (sugar pill) 5%.

Another group of colon cancer syndromes, termed hereditary nonpolyposis colorectal cancer (HNPCC) syndromes, also run in families. In these syndromes, colon cancer develops without the precursor polyps.

• HNPCC syndromes are associated with a genetic abnormality. This abnormality has been identified, and a test is available. People at risk can be identified through genetic screening.
• Once identified as carriers of the abnormal gene, these people require counseling and regular screening to detect precancerous and cancerous tumors.
• HNPCC syndromes are sometimes linked to tumors in other parts of the body.

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