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Aspirin benefits colorectal cancer patients in study

One of the most promising treatments for colorectal cancer could be sitting in your medicine cabinet.

A preliminary study suggests that aspirin - used for more than a century and sold for pennies a pill - could find new life as a weapon against colorectal cancer.

The study isn't definitive, but if the results hold up, "it borders on revolutionary," said Alfred Neugut of Columbia University's Mailman School of Public Health, who wasn't involved in the new study.

Aspirin appears to affect the growth of one type of colorectal cancer - that which overproduces the COX-2 enzyme, which promotes both inflammation and tumor growth, said Andrew Chan of Massachusetts General Hospital, co-author of a paper in Wednesday's Journal of the American Medical Association. Chan and his colleagues followed nearly 1,300 patients, all of whom received standard therapy for colorectal cancer, for nearly 12 years.

Among patients whose tumors overproduce COX-2, those who began aspirin after diagnosis had a 61 percent lower risk of dying from their colorectal cancer and a 38 percent lower risk of dying from any cause, the study said. Aspirin appeared to have no effect on tumors that don't overproduce COX-2. Aspirin also didn't help patients who took it before diagnosis, Chan said. About two-thirds of all colorectal cancer patients have tumors that overproduce COX-2.

Patients who benefited took the equivalent of one regular aspirin a day, Chan said.

Yet experts say it's too early to prescribe aspirin for colorectal cancer. The study had limitations. Although doctors observed patients, they didn't ask anyone to change their lifestyle or medications. So it's possible that people who chose to take aspirin after diagnosis are different in a way that affected their survival. In that case, aspirin couldn't really get credit for beating cancer, Neugut said.

Chan said the only way to truly prove that aspirin fights cancer is to conduct a "gold standard" trial, in which doctors randomly assign one group of people to take a drug, then compare their survival with that of people randomly assigned to a placebo.

Doctors in Singapore are already conducting such a trial, Neugut said.