Gene mutation allows aspirin's anti-polyp effect

Regular aspirin use reduces the risk of colon polyps in women with a common gene mutation that slows aspirin breakdown, a new study shows. In contrast, when this mutation is absent, aspirin seems to have no effect on polyp risk.

From 50 to 60 percent of the Caucasian population carries at least one copy of the variant gene, Andrew T. Chan of Massachusetts General Hospital in Boston told AMN Health.

Previous research has linked the mutation to a stronger effect of aspirin on polyp risk, he notes. "Our study extends these findings by demonstrating this in a" forward-looking study, which minimizes the chances that patients incorrectly remember their aspirin use, Chan said.

The investigation, which included 1,062 women participating in the Nurse's Health Study, also was able to evaluate the effects of aspirin use at different doses. The findings are published in the Journal of the National Cancer Institute.

In the 616 women with the gene mutation, the researchers found that those who took two or more standard aspirin tablets each week reduced their risk of polyps by 34 percent. The reduction increased with the dose, with women taking more than seven tablets weekly cutting their risk 59 percent.

But in women without the gene variant, aspirin did not cut the risk of polyps, and higher doses produced no increased benefit.

"I don't think we're prepared to say that it doesn't benefit people with the normal gene at all, but it does seem to be a smaller benefit," Chan said.

Before these findings can be applied clinically, he added, further studies are needed to determine if people with the gene variant are also more likely to experience side effects from aspirin, such as stomach bleeding.

Chan said his team also hopes to look at how the gene variation affects other outcomes related to aspirin use, such as the drug's cardioprotective effects.

In the meantime, he added, the only proven Colon cancer prevention method remains regular screening. "It's still very important that people pursue recommended screening for prevention."

SOURCE: Journal of the National Cancer Institute, March 15, 2005.