Metformin Use in Relation With Survival Outcomes of Patients With Renal Cell Carcinoma

Abstract

Purpose: To examine the effect of metformin use on survival outcomes in patients with renal cell carcinoma (RCC).

Methods: Retrospective analysis of 1528 RCC patients from 2 centers between 1992 and 2012 was conducted. A total of 390 diabetics with confirmed metformin use were included in the final analysis, with a median follow-up of 43.1 months. Primary outcomes were disease-free survival (DFS) and cancer-specific survival (CSS). Cox regression models were performed to evaluate the effects of potential predictors on DFS and CSS, following stratification of patients into local and metastatic disease.

Results: We identified 290 diabetics with localized and 100 with metastatic RCC. There were no clinicopathologic differences in the profiles of metformin users and non-metformin users. For patients with localized RCC, metformin users had significantly better DFS (hazard ratio, 0.47; P < .01) and CSS (hazard ratio, 0.21; P < .01) than non-users. There was no difference in CSS between metformin users and non-metformin users in diabetics with metastatic RCC (hazard ratio, 0.78; P = .286). Limitations include retrospective design and lack of data on metformin dosage and duration of use.

Conclusions: Metformin use is correlated with improved survival in patients with localized RCC, but not in metastatic RCC. Future studies should focus on its potential mechanisms and clinical utility.

Keywords: Biguanides; Cancer metabolism; Diabetes; Dimethylbiguanidine; Drug repurposing.