The role of metformin and statins in the incidence of epithelial ovarian cancer in type 2 diabetes: a cohort and nested case-control study.

OBJECTIVE: To obtain evidence of the effects of metformin and statins on the incidence of ovarian cancer in women with type 2 diabetes (T2D). DESIGN: A retrospective cohort study and nested case-control study. SETTING: The data were obtained from a diabetes database (FinDM) combining information from several nationwide registers. POPULATION: A cohort of 137 643 women over 40 years old and diagnosed with T2D during 1996-2011 in Finland. METHODS: In full cohort analysis Poisson regression was used to estimate the hazard ratios (HR) in relation to ever use of metformin, insulin other oral anti-diabetic medication or statins. In the nested case-control analysis 20 controls were matched to each case of ovarian cancer. Conditional logistic regression was used to estimate HRs in relation to medication use and cumulative use of different medications. The estimates were adjusted for age and duration of T2D. MAIN OUTCOME MEASURE: Incidence of ovarian cancer. RESULTS: In all, 303 women were diagnosed with ovarian cancer during the follow up. Compared with other forms of oral anti-diabetic medication, metformin (HR 1.02, 95% CI: 0.72-1.45) was not found to be associated with the incidence of ovarian cancer. Neither was there evidence for statins to affect the incidence (HR 0.99, 95% CI: 0.78-1.25). In nested case-control analysis the results were essentially similar. CONCLUSIONS: No evidence of an association between the use of metformin or statins and the incidence of ovarian cancer in women with T2D was found. TWEETABLE ABSTRACT: No evidence found for metformin or statins reducing the incidence of ovarian cancer.

Cause-specific mortality in endometrioid endometrial cancer patients with type 2 diabetes using metformin or other types of antidiabetic medication.

AIM: To obtain further evidence of the association between metformin or other types of antidiabetic medication (ADM) and mortality from endometrial cancer (EC) and other causes of death in patients with endometrioid EC and type 2 diabetes (T2D). MATERIALS AND METHODS: A retrospective cohort of women with existing T2D and diagnosed with endometrioid EC from 1998 to 2011, obtained from a nationwide diabetes database (FinDM), were included in the study. Cumulative mortality from EC and that from other causes was described by using the Aalen-Johansen estimator. Cause-specific mortality rates were analyzed by using Cox models, and adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were estimated in relation to the use of different forms of ADM during the three-year period preceding EC diagnosis. RESULTS: From the FinDM cohort we identified 1215 women diagnosed with endometrioid EC, of whom 19% were metformin users, 12% were users of other types of oral antidiabetic medication, 25% used other types of oral antidiabetic medication plus metformin, 26% used insulin and 14% had no antidiabetic medication. Mortality from EC was not found to be different in women using metformin (HR 0.89, 95% Cl 0.52-1.54) but mortality from other causes was lower (HR 0.52, 95% Cl 0.31-0.88) compared with women using other types of oral ADM. CONCLUSIONS: Our findings are inconclusive as to the possible effect of metformin on the prognosis of endometrioid EC in women with T2D. However, use of metformin may reduce mortality from other causes.