The results of previous studies aimed at evaluating the association between NSAIDs and breast cancer have been inconsistent. To get a more complete assessment of the association, Bahi Takkouche, M.D., Ph.D., of the University of Santiago de Compostela in Spain and colleagues performed a meta-analysis of data from 38 studies that in total involved 2,788,715 women.

Their findings were published in the Journal of the National Cancer Institute.

Regular use of any NSAID was associated with a relative risk reduction of 12 percent compared with non-users. A separate analysis for aspirin showed a 13 percent relative risk reduction, and an analysis for ibuprofen showed a 21 percent relative reduction in risk.

"The large number of studies included, the magnitude of the associations found, the consistency of the results through settings, and the existence of a mechanism that gives strong biologic plausibility to the relationship, provide evidence that NSAID use is associated with reduced risk for breast cancer," the authors conclude.

In an accompanying editorial, Louise R. Howe, Ph.D., of Weill Cornell Medical College in New York and Scott Lippman, M.D., of the University of Texas M. D. Anderson Cancer Center in Houston, discuss the likely reasons for inconsistencies between individual studies of NSAIDs and breast cancer risk. "Moving forward, analyses of associations between NSAID use and breast cancer risk will likely gain clarity from stratification based on the biology of NSAID action," they write.

SOURCE:
Journal of the National Cancer Institute, October 7, 2008