Aims/hypothesis: Diabetes has been associated with a statistically significantly increased risk of endometrial cancer in most, but not all studies. To provide a quantitative assessment of the association between diabetes and risk of endometrial cancer, we conducted a meta-analysis of case-control studies and cohort studies.
Subjects and methods: We identified studies by a literature search of PubMed and Embase through to January 2007 and by searching the reference lists of relevant articles. Summary relative risks (RRs) with 95% CIs were calculated using random-effects model.
Results: The analysis of diabetes (largely type 2) and endometrial cancer is based on 16 studies (three cohort and 13 case-control studies), including 96,003 participants and 7,596 cases of endometrial cancer. Twelve of the studies showed a statistically significantly increased risk and four a non-significant increased risk of endometrial cancer. In our meta-analysis we found that diabetes was statistically significantly associated with an increased risk of endometrial cancer (summary RR 2.10, 95% CI 1.75-2.53). The risk estimates were somewhat stronger among case-control (RR 2.22, 95% CI 1.80-2.74) than among cohort studies (RR 1.62, 95% CI 1.21-2.16), stronger among studies adjusting only for age (RR 2.74, 95% CI 1.87-4.00) compared with multivariate adjustment (RR 1.92, 95% CI 1.58-2.33) and slightly lower in studies performed in the USA than in those performed Europe. The analysis of type 1 diabetes and endometrial cancer was based on three studies and found a statistically significant positive association (summary RR 3.15, 95%CI 1.07-9.29).
Conclusions/interpretation: Results from the meta-analysis support a relationship between diabetes and increased risk of endometrial cancer.