The colon, or large intestine, is the last portion of the gastrointestinal tract and ends with the rectum. Cancer of the colon is the second most frequent cause of death from cancer in the United States.
The risk of colon cancer increases as people age 90 percent of colon cancers occur in individuals over 50 years of age.
Colon cancer is also more common in people with a family history of colon cancer, or a personal history of colon polyps or inflammatory bowel disease.
Cigarette smoking and excessive alcohol consumption may also increase the risk of colon cancer. Mutated versions of several genes have been linked to colon cancer.
For example, in their normal form the genes MSH2, MLH1, PMS1, and PMS2 correct tiny errors that occur when cells divide and grow.
Mutated versions of these genes cannot make such repairs, and eventually an accumulation of many such errors interferes with a cells ability to resist the uncontrolled division and growth that characterize cancer.
Research has linked the consumption of certain foods to colon cancer.The more red meat and animal fat that people eat, the greater their risk of developing colon cancer. Physicians continue to recommend low-fat, high-fiber diets as part of a healthy lifestyle to reduce the risk of high blood pressure, heart disease, and diabetes mellitus. Studies suggest that some drugs may decrease the risk of colon cancer.
For instance, estrogen replacement therapy after menopause and the use of nonsteroidal anti-inflammatory drugs such as ibuprofen appear to reduce the chances of developing this cancer.
Colon cancer usually develops slowly and may not present apparent symptoms in its early stages. Some individuals with undiagnosed colorectal cancer may detect blood in their bowel movements (feces). They may also experience persistent constipation or diarrhea, abdominal pain, or unexplained weight loss.
Two simple tests can detect most colon tumors while they are still in an early, easy-to-treat stage. The first test is the digital rectal examination, during which the physician uses a gloved finger to gently check the smoothness of the rectal lining.
The second test is the fecal occult blood test, in which a small sample of the patients feces is smeared on a card coated with a chemical called guaiac, which reacts with blood.
The card is analyzed in a laboratory for occult (hidden) blood. A positive result does not necessarily indicate the presence of cancer.
The primary treatment for colon cancer is surgery to remove the tumor. The surgery may be combined with radiation, chemotherapy, or both.
Using a combination of high-dose radiation and chemotherapy prior to surgery now makes it possible to avoid permanent colostomies in many patients who previously would have needed this procedure.
A colostomy is a surgical procedure to create an artificial opening through the abdominal wall to the exterior of the body for elimination of wastes into a plastic bag.
If cancer has spread from the colorectal area to the lymph nodes or liver, surgery or chemotherapy used in combination with three drugsfluorouracil, leucovorin, and irinotecanprolongs the lives of some patients. |
