An increased body mass index is associated with a worse prognosis in patients administered BCG immunotherapy for T1 bladder cancer

Purpose: The body mass index (BMI) may be associated with an increased incidence and aggressiveness of urological cancers. In this study, we aimed to evaluate the impact of the BMI on survival in patients with T1G3 non-muscle-invasive bladder cancer (NMIBC). Methods: A total of 1155 T1G3 NMIBC patients from 13 academic institutions were retrospectively reviewed and patients administered adjuvant intravesical Bacillus Calmette–Guérin (BCG) immunotherapy with maintenance were included. Multivariable Cox regression analysis was performed to identify factors predictive of recurrence and progression. Results: After re-TURBT, 288 patients (27.53%) showed residual high-grade NMIBC, while 867 (82.89%) were negative. During follow-up, 678 (64.82%) suffered recurrence, and 303 (30%) progression, 150 (14.34%) died of all causes, and 77 (7.36%) died of bladder cancer. At multivariate analysis, tumor size (hazard ratio [HR]:1.3; p = 0.001), and multifocality (HR:1.24; p = 0.004) were significantly associated with recurrence (c-index for the model:55.98). Overweight (HR: 4; p < 0.001) and obesity (HR:5.33 p < 0.001) were significantly associated with an increased risk of recurrence. Addition of the BMI to a model that included standard clinicopathological factors increased the C-index by 9.9. For progression, we found that tumor size (HR:1.63; p < 0.001), multifocality (HR:1.31; p = 0.01) and concomitant CIS (HR: 2.07; p < 0.001) were significant prognostic factors at multivariate analysis (C-index 63.8). Overweight (HR: 2.52; p < 0.001) and obesity (HR: 2.521 p < 0.001) were significantly associated with an increased risk of progression. Addition of the BMI to a model that included standard clinicopathological factors increased the C-index by 1.9. Conclusions: The BMI could have a relevant role in the clinical management of T1G3 NMIBC, if associated with bladder cancer recurrence and progression. In particular, this anthropometric factor should be taken into account at initial diagnosis and in therapeutic strategy decision making.