Because of conflicting reports regarding the relationship between pelvic inflammatory disease (PID) and ovarian cancer, we performed an updated meta-analysis to investigate the association between PID and the risk of this malignancy.

Embase, PubMed, and Web of Science were searched up until November 1, 2019. Hazard ratios (HRs), along with 95% confidence intervals (CIs), were calculated to analyse outcomes.

We included 16 studies in this meta-analysis. PID was associated with an increased risk of ovarian cancer (HR 1.18, 95% CI 1.13 to 1.22; I² = 41%). In subgroup analyses according to ethnicity, study design, tumour invasiveness, and type of ovarian cancer, PID was significantly associated with ovarian cancer in all subgroups. The lowest heterogeneity (I² = 0% to 38%) was observed for associations between PID and ovarian cancer in Asian patients (HR 1.25, 95% CI 1.10 to 1.42), ovarian cancer in case-control studies (HR 1.15, 95% CI 1.08 to 1.23), invasive ovarian cancer (HR 1.25, 95% CI 1.20 to 1.30), borderline ovarian cancer (HR 1.28, 95% CI 1.19 to 1.37), and non-serous ovarian cancer (HR 1.15, 95% CI 1.07 to 1.24).

This updated meta-analysis demonstrated that PID is associated with an increased risk of ovarian cancer. Future large, well-designed studies are necessary to corroborate our findings.