Diabetes mellitus and risk of ovarian cancer. A systematic review and meta-analysis of 15 cohort studies

Aim: Diabetes mellitus (DM) is hypothesized to be associated with an increased risk of ovarian cancer (OC), but current evidences are inconsistent. We aimed to further study this association. Methods: PubMed, EMBASE, Web of Science, and Scopus were searched for eligible articles. After descriptive summary of the data, a random-effects model was applied in quantitative synthesis. Subgroup analysis was performed by study locales and settings, and sensitivity analysis was conducted based on restrictive selection criteria. Funnel plots and the Egger's test were used to assess publication bias. Statistical heterogeneity in meta-analysis was assessed by the P value derived from the Cochrane Q statistic and I-squared value. Results: Fourteen articles involving data of 15 cohort studies were included for our research. Overall, 17 risk ratios (RRs) were synthesized and yielded a pooled RR of 1.32 (95% CI: 1.14-1.52, P-Cochrane < 0.001, I-2 = 79.8%). Thirteen RRs were synthesized for type 2 DM, and the pooled RR was 1.24 (95% CI: 1.06-1.44, P-Cochrane < 0.001, I-2 = 81.8%). Four RRs were synthesized for type 1 DM, and the result was significant (RR: 1.83, 95% CI: 1.21-2.78, P-Cochrane = 0.080, I-2 = 55.7%). Results of sensitivity analysis suggested the robustness of a positive association between DM and OC risk, and subgroup analysis demonstrated that the association between DM and OC was much more substantial among Asia population. No publication bias was identified in meta-analysis. Conclusion: Our study suggests there is a moderate relative increase in the risk of OC among DM patients. Future studies should investigate the effect of duration of DM and antidiabetes intervention to OC risk. (C) 2017 Elsevier B.V. All rights reserved.