Gene Mutation Influences Aspirin's Colon Cancer Benefit

TUESDAY, June 25 (HealthDay News) -- Regular aspirin use is associated with a lower risk of developing colorectal cancer, but only cancers without mutations in the BRAF oncogene, according to a study published in the June 26 issue of the Journal of the American Medical Association.

Reiko Nishihara, Ph.D., from the Dana-Farber Cancer Institute in Boston, and colleagues analyzed data from 127,865 participants in two large studies to examine the association between aspirin intake and colorectal cancer risk based on the presence of tumor mutations in the BRAF oncogene.

The researchers found that there were 1,226 incident rectal and colon cancers during follow-up. After adjusting for various factors, regular aspirin use was associated with a lower risk of BRAF-wild-type cancer (hazard ratio [HR], 0.73) but not BRAF-mutated cancer (HR, 1.03). The association was unaffected by the status of tumor prostaglandin-endoperoxide synthase 2 expression or PIK3CA or KRAS mutation. Increasing the number of aspirin tablets per week lowered the risk of BRAF-wild-type cancer (HR, 0.43 for >14 tablets per week), while more tablets had no effect on the risk of BRAF-mutated cancer.

"Regular aspirin use was associated with lower risk of BRAF-wild-type colorectal cancer but not with BRAF-mutated cancer risk," Nishihara and colleagues conclude. "These findings suggest that BRAF-mutant colon tumor cells may be less sensitive to the effect of aspirin."

One author has been a consultant for several pharmaceutical companies.

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