The impact of metformin on survival in diabetic endometrial cancer patients: a retrospective population-based analysis.

Purpose: The aim of our study was to assess overall survival and cancer-specific survival in endometrial cancer patients with type 2 diabetes mellitus (T2DM) using metformin.

Methods: Patients with endometrial cancer and T2DM during 2000-2012 period were identified from the Lithuanian Cancer Registry and the National Health Insurance Fund database. Cancer-specific and overall survival were primary outcomes.

Results: In our study we included 6287 women with endometrial cancer out of whom 664 were diagnosed with T2DM (598 metformin users and 66 never users). During follow-up (mean follow-up time was 8.97 years), no differences in risk of endometrial cancer specific mortality was observed in diabetic patients treated with metformin (Hazard Ratio (HR) 0.87, 95% Confidence Interval (CI) 0.70-1.07). Overall mortality in the diabetic metformin ever users' group was significantly higher compared with the non-diabetic endometrial cancer women (HR 1.17, 95% CI 1.03-1.32) and in the group of metformin never users with T2DM (HR 1.42, 95% CI 1.07-1.87).

Conclusion: Our study results suggest no beneficial impact on overall and cancer-specific survival in endometrial cancer patients who were treated with metformin as part of their diabetes treatment.

Supplementary Information: The online version contains supplementary material available at 10.1007/s40200-023-01358-3.