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," says Alfred Neugut of Columbia University's Mailman School of Public Health, who wasn't involved in the study.
Aspirin appears to affect the growth of one type of colorectal cancer -- one that overproduces the COX-2 enzyme, which promotes both inflammation and tumor growth, says Andrew Chan of Massachusetts General Hospital, co-author of a paper in today'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% lower risk of dying from their colorectal cancer and a 38% lower risk of dying from any cause, the study says. 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 says. 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 says.
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 living habits or medications. So it's possible that people who chose to take aspirin after diagnosis were different in a way that affected their survival. In that case, aspirin couldn't really get credit for beating cancer, Neugut says.
Chan says the only way to prove 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 conducting such a trial, Neugut says.
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