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Colon Cancer: The Need for Early Screening.

If all men and women over 50 were screened for colon cancer, experts estimate that the death rate could be cut by one third. About 131,000 new cases of colorectal cancer are expected in 1999, with 55,000 deaths from the disease--the second most common cause of cancer death in the United States. Yet too few Americans are being screened for the disease.

Understandably, most of us are not very keen about having a tube inserted up the rectum, nor in smearing stool specimens on a card. And too few doctors, apparently, are insisting that their patients undergo these tests. With these tests, however, up to 90 percent of these cancers would be detected early enough to be cured. When the cancer spreads beyond the intestinal tract to the lymph nodes, fewer than 50 percent of patients have a chance of cure.

Small outgrowths on the lining of the colon or rectum are the source of most colorectal cancers. Known as adenomatous polyps (or, more commonly, just polyps), these occur in about 30 percent of adults by age 50 and in more than half of us who turn 70. Most colorectal polyps produce no symptoms, and only occasionally do they bleed. Fortunately, fewer than one percent of intestinal polyps become malignant, but when cancerous changes do occur, early detection greatly increases the likelihood of cure.

The American Cancer Society estimates that 15 to 30 percent of us have a genetic predisposition to colorectal cancer; a more recent study by Johns Hopkins University puts that estimate at 5 to 10 percent. Regardless of the odds, if you have a family history of the disease, that puts you at a higher risk of getting the disease. Other factors predisposing one to colon cancer include too much red meat in the diet; too little consumption of vegetables, fruits, and other sources of dietary fiber; too much alcohol; smoking; obesity; too little exercise; and having ulcerative colitis or Crohn's disease.

The Agency for Health Care Policy and Research (AHCPR) developed two new sets of screening guidelines last year, basing its results on a review of some 3,500 published studies on colon cancer. One set is for persons over 50 with an average risk of colon cancer, and the other is for those of all ages with a family history of the disease or a personal history of colorectal polyps.

For those over 50 without previous polyps or a family history of colorectal cancer:

* An annual fecal occult blood test, in which a tiny bit of stool is rubbed on a card to be mailed to the testing laboratory. The test is more accurate if one has not taken aspirin, vitamin C supplements, or eaten red meat or certain raw vegetables and fruits shortly before the test. Although it will detect intestinal bleeding from any cause, and may miss a cancer not bleeding at the time of the test, fecal occult blood testing does save lives.

* Flexible sigmoidoscopy every five years. Because the sigmoidoscope only visualizes the lower third of the intestine, the entire colon must then be examined with a colonoscope if a polyp is found.

* An alternative to sigmoidoscopy is the barium enema x-ray, done every five to ten years. Again, however, colonoscopy must follow if a polyp is found.

* Another alternative is to omit both the fecal occult blood test and flexible sigmoidoscopy, and have a colonoscopy every ten years.

The other set of guidelines for persons with a family history of disease or personal history of colorectal polyps involves initial screening at a younger age, with more frequent follow-up screening, depending on individual circumstances. Although genetic screening is a possibility, it is recommended only when a rare form of inherited colorectal cancer, which strikes people under age 40, has occurred in other close family members.

Strangely, postmenopausal women taking hormone replacement therapy seem to have less cancer, for reasons not yet understood. Adequate calcium intake also seems to play a positive role in colon cancer, as does an adequate amount of folate (400 micrograms daily)--either in food or by supplements.

Removal of polyps which have undergone precancerous changes is often all that is required to prevent colon cancer. Should surgery become necessary, however, colostomy (in which the remaining end of the colon drains into a bag attached to an opening in the abdomen) is required in only about 5 percent of patients with colon cancer.

RELATED ARTICLE: Aspirin for Colon Cancer

Not to treat it, but possibly to prevent it, particularly if you have a family history of colon cancer. Researchers have found that among persons taking aspirin to prevent heart attacks, the risk of colon cancer was also reduced, Aspirin acts upon blood platelets, one of the factors necessary for blood to clot, By making the platelets less "sticky," aspirin reduces the likelihood that the platelets will stick together and form a blood clot that can block a coronary artery. As for the possible role in the prevention of colon cancer, aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) may act by suppressing cell proliferation through inhibiting the synthesis of prostaglandins, compounds that regulate many different processes in the body.

To reduce the risk of stomach irritation, which can lead to, ulcers and bleeding, the current recommendation is to take low-dose (81 mg) baby aspirin. Recent studies show, however, that this may be too small a daily dose for everyone, leading to a new recommendation that, in addition to the daily low-dose aspirin, one can take an adult aspirin (325 mg) twice a month--for example, on the first and the 15th.
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Publication:Medical Update
Date:Jan 1, 1999
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