Aspirin, other painkillers may not reduce colorectal cancer risk for everybody

Regular use of aspirin and NSAIDs —nonsteroidal anti-inflammatory drugs — seems to reduce colorectal cancer risk in population studies. Yet a new study finds that people who harbor one of two genetic variants seem to have a heightened risk of the cancer if they take aspirin or NSAIDs, drugs that include ibuprofen and naproxen.

About 4 percent of people in the study carried one of these two rare variants, which are located in the vicinity of the MGST1 gene on chromosome 12. In this analysis, which appears in the March 17 JAMA, an international research team also detected a third genetic variant, this one in the neighborhood of the IL16 gene on chromosome 15. People carrying that variant, about 9 percent of participants, seemed to gain no protection from the drugs. Both MGST1 and IL16 belong to families of genes that have been linked to cancer. But the precise mechanisms that might associate these variants with colorectal cancer risk and aspirin or NSAID use remain unclear.

An earlier study found that people carrying a mutation in the PIK3CA gene on chromosome 3 seemed to gain better-than-usual protection against colorectal cancer from taking aspirin (SN Online,10/24/12). The new study was based on data from more than 8,000 colorectal cancer patients and more than 8,000 others who didn’t have the cancer.