Type 2 diabetes mellitus predicts worse outcomes in patients with high-grade T1 bladder cancer receiving bacillus Calmette-Guérin after transurethral resection of the bladder tumor

Objectives: The aim of this multicenter study was to investigate the prognostic role of type 2 diabetes mellitus (T2DM) comorbidity in a large multi-institutional cohort of patients with primary T1HG/G3 non–muscle-invasive bladder cancer (NMIBC) treated with transurethral resection of the bladder (TURB). Materials and methods: A total of 1,172 patients with primary T1 HG/G3 who had NMIBC on re-TURB and who received adjuvant intravesical bacillus Calmette-Guérin therapy with maintenance were included. Endpoints were recurrence-free survival and progression-free survival. Results: A total of 231 (19.7%) of patients had T2DM prior to TURB. Five-year recurrence-free survival estimates were 12.5% in patients with T2DM compared to 36% in patients without T2DM, P < 0.0001. Five-year PFS estimates were 60.5% in patients with T2DM compared to 70.2% in patients without T2DM, P = 0.003. T2DM was independently associated with disease recurrence (hazard ratio = 1.41; 95% confidence interval = 1.20–1.66, P < 0.001) and progression (hazard ratio = 1.27; 95% confidence interval = 0.99–1.63, P < 0.001), after adjusting for other known predictive factors such as tumor size, multifocality, T1G3 on re-TURB, body mass index, lymphovascular invasion, and neutrophil-to-lymphocytes ratio. Conclusions: Given the potential implications for management, prospective validation of this finding along with translational studies designed to investigate the underlying biology of such an association are warranted.