Effect of statin on risk of gynecologic cancers: a meta-analysis of observational studies and randomized controlled trials.

Objective. Epidemiologic and clinical findings are inconsistent concerning the risk for gynecologic cancers associated with statin use. We conducted a detailed meta-analysis of all relevant original studies to evaluate the effects of statin on the risk of gynecologic cancers. Methods. We searched PubMed, Embase, and Cochrane library databases up to February 2014 looking for eligible studies. Summary relative risk (RR) estimates and 95% confidence intervals (CIs) were used to calculate the risk using random-effects models. Results. A total of 14 (4 randomized controlled trials, 5 cohorts, and 5 case-control) studies, involving 12,904 gynecologic cancer cases, contributed to the analysis. Pooled results indicated a non-significant decrease of total gynecologic cancer risk among statin users (RR=0.89; 95% CI, 0.78-1.01). Stratified analyses across cancer site revealed a modest protective effect of statin on ovarian cancer (RR=0.79; 95% CI, 0.64-0.98), while no association was found for endometrial cancer (RR=0.90; 95% CI, 0.75-1.07). The effect of statin use against cervical cancer and vulvar cancer is not conclusive. Furthermore, long-term statin use (>5years use) did not significantly affect the risk of endometrial cancer (RR=0.69; 95% CI, 0.44-1.10), but had an obvious decrease on the risk of ovarian cancer (RR=0.48; 95% CI, 0.28-0.80). Conclusions. Our results suggest that statin use was inversely associated with ovarian cancer risk, and the association was stronger for long-term statin use (>5years). The evidence for a protective effect of statin use against other gynecologic cancers is suggestive but not conclusive, which deserves further investigation.