The obesity paradox: defining the impact of body mass index and diabetes mellitus for patients with non-muscle-invasive bladder cancer treated with bacillus Calmette-Guérin.

Abstract

To evaluate if the obesity paradox, wherein obesity portends worse overall prognosis for a disease but improved outcomes for patients receiving immunotherapy, exists for patients receiving bacillus Calmette-Guérin (BCG) in a contemporary cohort. We performed an Institutional Review Board-approved database review to identify patients with non-muscle-invasive bladder cancer (NMIBC) completing at least an induction course of BCG. Clinicopathological variables collected included: body mass index (BMI), medications, and diabetes mellitus (DM). Outcomes of interest included: recurrence-free (RFS), progression-free (PFS), cancer-specific (CSS), and overall survival (OS). Univariate and multivariate modelling were used to evaluate the association between outcomes and clinical factors. A total of 579 patients (median follow-up 4.6 years) received BCG induction for NMIBC; 90% had high-grade disease (47.2% clinical stage T1). In all, 75.7% of patients were overweight or obese and 18% had DM. Aspirin, statins, metformin and β-blockers were used in 34%, 42%, 11%, and 29% of patients, respectively. Overweight and obese patients had improved PFS, CSS and OS. DM was associated with worse RFS. Medications of interest had no association with outcomes. Elevated BMI is associated with improved outcomes in patients with NMIBC treated with BCG immunotherapy. Patients with DM are at increased risk of recurrence. These findings support a potential obesity paradox in bladder cancer. Evaluation of the underlying mechanism and the role of global patient assessment, counselling, and risk factor modification are warranted.