Aspirin's Anti-Colon Cancer Effect May Depend on Genes

Tumors with a key mutation seemed unaffected by daily use of the drug, study found

By Robert Preidt

HealthDay Reporter

TUESDAY, June 25 (HealthDay News) -- Numerous studies have found that daily low-dose aspirin might help shield against colon cancer. But new research suggests that gene mutations found in different colon tumors may influence that relationship.

This study of data from more than 127,000 people in the Nurses' Health Study and the Health Professionals Follow-Up Study in the United States found that the benefits of aspirin used were affected by mutation of a gene called BRAF.

Specifically, regular aspirin use was associated with a lower risk of colorectal cancers characterized by the "typical" form of BRAF, but not with the risk of colon cancers with mutated forms of BRAF.

These findings suggest that BRAF-mutant colon tumor cells may be less sensitive to the effects of aspirin, according to the study in the June 26 issue of the Journal of the American Medical Association.

The researchers also found that taking a higher number of aspirin tablets a week -- more than 14 tablets -- was associated with a lower risk of colorectal cancer with typical BRAF, but this was not seen with BRAF-mutated cancers, according to a journal news release.

The research was led by Reiko Nishihara of the Dana-Farber Cancer Institute in Boston.

Importantly, regular aspirin use after a diagnosis of either type of colorectal cancer did not improve patients' survival, the team said.

"This suggests that the potential protective effect of aspirin may differ by BRAF status in the early phase of tumor evolution before clinical detection but not during later phases of tumor progression," the study authors wrote.

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