Association between pelvic inflammatory disease and ovarian cancer: A bidirectional Mendelian randomization study.

Some observational studies have suggested an association between pelvic inflammatory disease (PID) and ovarian cancer (OC), but the causality between PID and OC remains unclear. To investigate the causal association between PID and 7 OCs, we performed two-sample bidirectional Mendelian randomization (MR) analyses using genetic variants associated with PID. Pooled data on OC were obtained from the Ovarian Cancer Association Consortium. Effect estimates were obtained by inverse-variance weighting, the weighted median method, MR-Egger regression, and MR pleiotropy residual sum and outlier (MR-PRESSO) tests. The results of the inverse-variance weighting analysis showed that PID incidence risks were not significantly associated with OC, mucinous OC, low malignant potential OC, low-grade serous OC, high-grade serous OC, endometrioid OC, or clear cell OC. In this study, the causalities between PID and 7 OCs were comprehensively assessed, but the identified genetic evidence suggested no possible causalities between PID and 7 OCs in European populations.