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.

OBJECTIVES: 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.

PATIENTS AND METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.