Impact of diabetes mellitus on oncologic outcomes in patients receiving robot-assisted radical cystectomy for bladder cancer

Purpose Aim of this study is to investigate the association between DM and oncological outcomes among patients with muscle-invasive (MI) or high-risk non-muscle invasive (NMI) bladder cancer (BC) who underwent robot-assisted radical cystectomy with intracorporeal urinary diversion (RARC). Methods An IRB approved multi-institutional BC database was queried, including patients underwent RARC between January 2013 and June 2023. Patients were divided into two groups according to DM status. Baseline, clinical, perioperative, pathologic data were compared. Chi-square and Student t tests were performed to compare categorical and continuous variables, respectively. Kaplan-Meier method and Cox regression analyses were performed to assess the association between DM and oncologic outcomes. Results Out of 547 consecutive patients, 97 (17.7%) had DM. The two cohorts showed similar preoperative features, except for ASA score (p = 0.01) and Hypertension rates (p < 0.001). No differences were detected for perioperative complications, pT stage, pN stages and surgical margins status (all p > 0.12). DM patients displayed significantly lower 5-yr disease-free survival (DFS) (44.6% vs. 63.3%, p = 0.007), 5-yr cancer-specific survival (CSS) (45.1% vs. 70.1%, p = 0.001) and 5-yr Overall survival (OS) (39.9% vs. 63.8%, p = 0.001). At Multivariable Cox-regression analyses DM status was identified as independent predictor of worse cancer-specific survival (CSS) (HR 2.1; p = 0.001) and overall survival (OS) (HR 2.05; p < 0.001). Conclusion Among BC patients who underwent RARC, DM patients showed worse oncologic outcomes than the non-DM patients, with DM status playing an independent negative predicting role in CSS and OS. Future prospective studies are awaited, stimulating basic and translational research to identify possible mechanisms of interaction between DM and BC.