Use of statins and risk of ovarian cancer: evidence on effect modification by parity, menopause and endometriosis from nationwide nested case-control studies

OBJECTIVE: Previous results on the association between statin use and risk of ovarian cancer (OC) are inconsistent, warranting further investigation. This study aims to examine the association between statin use and risk of OC in a large study population.

METHODS: Based on two nationwide nested case-control studies utilizing data from Danish and Swedish high-quality registries, we identified 11,874 OC cases who were individually matched on age to 474,960 controls using risk-set sampling. Conditional logistic regression was performed separately on the country-specific data to calculate odds ratios (ORs) and corresponding 95 % confidence intervals (CIs) for the association between statin use and risk of OC. Country-specific estimates were combined based on a fixed-effect assumption. Furthermore, we examined potential effect modifications by a priori selected OC risk factors on the association between statin use and OC risk.

RESULTS: We found no overall association between statin use and risk of OC (OR = 0.96; 95 % CI: 0.91-1.01); neither with duration nor intensity of use. However, statin use was associated with a decreased risk of OC in subsets of women with endometriosis (OR = 0.70; 95 % CI: 0.53-0.91), and nulliparous women (OR = 0.86; 95 % CI: 0.79-0.93).

CONCLUSION: We found an effect modification of some known ovarian cancer risk factors on the association between statin use and risk of OC. In women with endometriosis, and in nulliparous women, respectively, statin use was associated with a decreased risk of OC, suggesting statins may have potential as a preventive measure.