• Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Drive, Rockville, MD, 20850, USA. sarah.irvin@nih.gov.
• Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Drive, Rockville, MD, 20850, USA.

PURPOSE: The link between lipid-stabilizing medications and epithelial ovarian carcinogenesis is incompletely understood. Statins may reduce ovarian cancer risk, but results are inconclusive.

METHODS: We conducted a systematic review and meta-analysis of studies reporting associations between statin use and ovarian cancer risk in PubMed. Summary risk ratios (RRs) and confidence intervals (CIs) were calculated. Subgroup analyses by cancer histotype, statin class (lipo- or hydrophilic) and duration of statin use were conducted. Use of individual statins in populations was assessed to determine population-specific differences in statin types.

RESULTS: Nine studies with 435,237 total women were included (1 randomized controlled trial (RCT); 4 prospective; 4 case-control). Statin use was associated with a reduced risk of ovarian cancer (RR 0.87, 95% CI 0.74-1.03) and risk was significantly reduced in populations with low pravastatin use (RR 0.83, 95% CI 0.70-0.99). Risk estimates varied by statin class (3 studies; lipophilic: RR 0.88, 95% CI 0.69-1.12; hydrophilic: RR 1.06, 95% CI 0.72-1.57) and cancer histotype (3 studies; serous: RR 0.95, 95% CI 0.69-1.30; clear cell: RR 1.17, 95% CI 0.74-1.86). Long-term use was associated with a reduced risk of ovarian cancer (RR 0.77, 95% CI 0.54-1.10) that further reduced when pravastatin use was low (RR 0.68, 95% CI 0.46-1.01). Between-study heterogeneity was high overall and in subgroups (I² > 60%).

CONCLUSION: Statins may be associated with a reduced risk of ovarian cancer, but the effect likely differs by individual statin, duration of use and cancer histotype. Additional well-powered studies are needed to elucidate important subgroup effects.