Association between diabetes mellitus and oncological outcomes in bladder cancer patients undergoing radical cystectomy

Objective: To determine the association between diabetes mellitus and oncological outcomes in urothelial bladder cancer patients undergoing radical cystectomy. Methods: From January 2004 to December 2014, 200 non-metastatic urothelial bladder cancer patients who underwent radical cystectomy were divided into two groups according to diabetes mellitus status at the time of surgery. Kaplan-Meier and Cox regression analysis were used to assess the association between diabetes mellitus and urothelial bladder cancer recurrence-free, cancer-specific and overall mortality. Results: Of the 200 patients, 28 (14%) had diabetes mellitus and presented similar preoperative factors and pathological findings after radical cystectomy, including pathological stage, grade, lymph node invasion and positive surgical margin compared with non-diabetes mellitus patients (n = 172). The 5-year cancer-specific survivals were 92.3% and 62.1% in the non-diabetes mellitus and diabetes mellitus groups, respectively (P = 0.022). Multivariate Cox regression analysis showed that diabetes mellitus was a significant predictor for cancer-specific mortality (hazard ratio 1.785, P = 0.038). The 5-year overall survival rate was 92.1% and 59.4% in the non-diabetes mellitus and diabetes mellitus groups, respectively (P = 0.014), and diabetes mellitus was a significant factor for overall mortality by multivariate Cox regression analysis (hazard ratio 1.281, P = 0.042). Conclusions: Among bladder cancer patients who underwent radical cystectomy, the diabetes mellitus patients had worse cancer-specific mortality and overall mortality outcomes than the non-diabetes mellitus patients. The mechanism of association between diabetes mellitus and urothelial bladder cancer should be investigated to validate the present results in a future prospective study.