Metformin improve upper tract urothelial carcinoma survival in Taiwanese patients with type 2 diabetes

Purpose: The oral diabetes medicine metformin might have chemopreventive effects against cancer which was discussed before. However, no clinical study exists for analyzing the effect of metformin in upper tract urothelial carcinoma survival condition in type 2 diabetes patients which presents an unusual feature in Taiwan. Therefore, we want to realize if metformin can improve survival rate in upper tract urothelial carcinoma patients through a population-based analysis.

Materials and Methods: The reimbursement databases of all Taiwanese patients with a newly diagnosis of upper tract urothelial carcinoma between 2003 and 2011 (n = 4418) were retrieved from the National Health Insurance. Then we just extract type 2 diabetes mellitus patients with more than two prescriptions diabetes mellitus drugs and delete only 1 prescription of metformin in prior 6 months (n = 826). We calculate hazard ratios by Cox regression for ever-users and never-users with SAS statistical method.

Results: Among 826 enrolled patients, there are 358 patients never using metformin and 468 ever take more than 2 prescription of metformin. 314 patients are male and 512 are female. The median survival time is 4.25 years for never using metformin and 6.97 years for ever-users and the difference is significant statistically. (P = 0.0005) We also assess subgroup of patients who received standard operation of nephroureterectomy and it also revealed metformin have better survival rate.

Conclusion: This study suggests that metformin use is associated with improving survival rate of upper tract urothelial carcinoma in patients with T2DM.