Diabetes mellitus and ovarian cancer risk: a systematic review and meta-analysis of observational studies.

Objective: The objective of this study was to evaluate the epidemiologic association between diabetes and risk of ovarian cancer.

Methods: We searched PubMed, EMBASE, and The Cochrane Library for observational studies on the association between diabetes and ovarian cancer. Cohort studies that reported relative risks (RRs) and case-control studies that showed odds ratios were included in the analysis. Summary RRs with 95% confidence intervals (CIs) were calculated with a random-effects model.

Results: A total of 19 studies from 18 articles (7 case-control studies and 11 cohort studies) met the inclusion criteria. Combining data from all studies, diabetes was associated with an increased risk of ovarian cancer, compared with no diabetes (summary RR of ovarian cancer incidence, 1.17; 95% CI, 1.02-1.33). In cohort and nested case-control studies, patients with diabetes had statistically significant increased risk of ovarian cancer (RR, 1.16; 95% CI, 1.01-1.33), without significant heterogeneity (I = 27; P = 0.172). Among studies that control for age, body mass index, smoking, and alcohol, a prominent association between diabetes and ovarian cancer was found (RR, 1.55; 95% CI, 1.11-2.19).

Conclusions: This study suggests that women with diabetes have a moderately increased risk of ovarian cancer.