Abstract Background Renal cell carcinoma (RCC) is a major urologic malignancy worldwide, with obesity recognized as a known risk factor. Interestingly, a higher body mass index (BMI) has been associated with improved outcomes in immunotherapy, a phenomenon termed the “obesity paradox.” This study investigates the influence of BMI on the effectiveness of immune combination therapies in Japanese patients with metastatic RCC. Methods A retrospective study was conducted on 243 Japanese patients with metastatic RCC who received immune combination therapies between 2018 and 2022. Patients were stratified into two groups: non-overweight/obesity (BMI < 25 kg/m 2 ) and overweight/obesity (BMI ≥ 25 kg/m 2 ). Survival outcomes, including progression-free survival (PFS) and overall survival (OS), were compared between the groups. Results There was no significant difference in PFS between the groups. However, the overweight/obesity group showed a trend toward longer OS, particularly in patients receiving IO–IO regimens (P = 0.011). In contrast, although no statistically significant difference was observed in the IO–TKI regimen, there was a trend toward prolonged OS in the non-overweight/obesity group. No significant differences in immune-related adverse events were observed between the groups. Conclusion Higher BMI may be associated with better outcomes in immune combination therapy, especially with IO–IO regimens. These findings suggest that BMI could be a useful factor in optimizing RCC treatment. Further research with larger cohorts is needed to confirm these results and understand the mechanisms behind the “obesity paradox.”
Anami et al. (Wed,) studied this question.