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Baby aspirin may prevent colon cancer

By LARRY SCHUSTER, UPI Science News

SAN FRANCISCO, April 7 (UPI) -- Baby aspirin may prevent many cases of colorectal cancer but adult doses were less effective, researchers at a cancer conference said Sunday.

In the North American study of 1,100 patients in their 50s and 60s, scientists found those taking 80 milligrams of aspirin per day reduced their risk of recurrent polyps, or adenomas -- precursors to malignant cancer -- by 19 percent. Patients taking 325 mg of aspirin had a 4 percent risk reduction.

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The data appeared to be more striking, however, in the prevention of more aggressive adenomas, called tubulovillus or villous. In those, baby aspirin reduced risk by 40 percent compared to just 19 percent for the higher dose in this study, the first clinical trial that looked at the preventive effects of aspirin in the development of tumors in the large bowel.

"Very clearly aspirin helps" prevent cancer, said Dr. John A. Baron, of Dartmouth Medical School, Lebanon, N.H. Noting aspirin's low risk of causing bleeding and stroke, however, it still is too early to recommend it for healthy people throughout the population based on the results of the study.

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In fact, low-dose aspirin may have had more of a preventive effect than the numbers reported at the annual conference of the American Association for Cancer Research. The data were based on a single colonoscopy, done at a median of 34 months after treatment began. Another colonoscopy might have shown a greater benefit if the study had been carried out over a longer period, Baron said at a news briefing.

All patients in the study had at least one adenoma removed within the three months preceding the study and had no known cardiovascular disease or other conditions usually treated with aspirin. They also had no hereditary cancer syndromes.

AACR spokesman Allan H. Conney, director of the Laboratory for Cancer Research at Rutgers University, Piscataway, N.J., told United Press International, "There is a background of research both in animal models and human epidemiological studies indicating that people who are ingesting aspirin chronically have a lower risk of colon cancer."

Conney said in this study, "The interesting thing to me seemed to be the greater effect of the aspirin on the more progressive, serious type of adenomas."

It might be that aspirin prevents progression to malignant cancer, Conney added.

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