Breast cancer and NSAID use: a meta-analysis

Recent epidemiological studies suggest that non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of several cancers including breast cancer. This meta-analysis examined the studies on NSAID use and breast cancer. The estimators of relative risk and associated variances, which have been adjusted for the greatest number of confounders, were abstracted and included in the meta-analysis. Combined estimators of relative risk (RR) were calculated using either fixed or random effect models. Meta-analyses were performed on 6 cohort studies (number of cases ranged from 14 to 2414) and 8 case–control studies (number of cases ranged from 252 to 5882). The combined estimate of relative risk was 0.82 (95% confidence interval [CI] = 0.75–0.89). The combined estimate for cohort studies was 0.78 (95% CI = 0.62–0.99) and was 0.87 (95% CI = 0.84–0.91) for case–control studies. The findings of this meta-analysis suggest that NSAID use may be associated with a small decrease in the risk of breast cancer. However, the available data are insufficient to estimate the dose–response effect for duration and frequency of use of any particular types of NSAID. © 2001 Cancer Research Campaign http://www.bjcancer.com