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High doses of aspirin may ward off colon cancer

Long-term use of aspirin does help ward off colon cancer, but only at high doses that could cause gastrointestinal bleeding, researchers said.
/ Source: Reuters

Long-term use of aspirin does help ward off colon cancer, but only at high doses that could cause gastrointestinal bleeding, researchers said on Tuesday.

Previous studies have shown that patients with a history of colon polyps or colon cancer who take aspirin regularly can prevent recurrence, and researchers at Massachusetts General Hospital and Brigham and Women’s Hospital in Boston sought to determine at what levels the painkillers were effective.

“Our study did find a protective effect of long-term aspirin use on risk of invasive colorectal cancer, but only at dosage levels considerably higher than those used to prevent cardiovascular disease,” said Dr. Andrew Chan of Massachusetts General Hospital.

To stem cardiovascular disease, some people take “baby” aspirin, which is one-fourth the dose of full-strength aspirin, daily.

The maximum benefit from full-strength aspirin was a 53 percent lower risk of colon cancer among female patients who took more than 14 tablets a week for more than 10 years. The reduction in cancer risk declined along with aspirin dose --disease risk was cut by 22 percent for those taking between six and 14 tablets a week.

But for every one or two cases of cancer prevented by taking high doses of aspirin, eight people would develop serious gastrointestinal bleeding, the researchers estimated.

Second leading cause of cancer deaths
Writing in the Journal of the American Medical Association, the researchers reserved judgment on whether to recommend aspirin or other painkillers such as ibuprofen and naproxen to lessen colon cancer risk.

Aspirin and other non-steroidal anti-inflammatory drugs other than acetaminophen appear to lower the risk of colon polyps, at least in part, by inactivating the COX-2 enzyme that involves inflammation and may stimulate tumor development, the researchers said.

There are expected to be 145,000 new U.S. cases of colon cancer diagnosed this year and 56,000 deaths from the disease, second only to lung cancer as the leading cause of cancer death.

The American Cancer Society recommended against taking aspirin for the purpose of protecting against colon cancer because of the bleeding risk.

The findings, which are also thought to apply to men, came from the Nurses’ Health Study that has followed more than 120,000 female registered nurses since the mid-1970s.