Sex differences in the prognostic value of body mass index after curative nephrectomy for high-risk renal cell carcinoma: a multicenter cohort study.

BACKGROUND

Higher body mass index (BMI) has been associated with favorable prognosis in renal cell carcinoma (RCC), a phenomenon known as the "obesity paradox". However, this relationship may differ by sex. Moreover, previous studies have insufficiently accounted for laboratory-based nutritional status and mainly focused on low-risk populations. Consequently, the prognostic value of BMI in patients with high-risk localized RCC remains unclear.

METHODS

We conducted a retrospective multicenter study of patients with high-risk localized RCC who underwent curative surgery between 2010 and 2022. Patients were stratified by BMI (≥ 25 vs. < 25 kg/m2) and sex. Disease-free survival (DFS) and overall survival (OS) were evaluated using Kaplan-Meier analysis and Cox proportional hazards models adjusted for clinicopathological variables and laboratory-based nutritional biomarkers.

RESULTS

A total of 668 patients were included, of which 243 developed disease recurrence during follow-up. In the overall cohort, BMI ≥ 25 kg/m2 was significantly associated with longer DFS and OS. A significant interaction between BMI and sex was observed (P = 0.043), indicating that the prognostic value of BMI differed between males and females. In multivariable sex-stratified analyses, higher BMI was independently associated with improved DFS in males (hazard ratio = 0.61), but not in females. This relationship remained robust after adjustment for laboratory-based nutritional biomarkers and in sensitivity analyses restricted to patients with preserved nutritional status.

CONCLUSION

Higher BMI was independently associated with more favorable oncological outcomes in patients with high-risk localized RCC, particularly in males. BMI may therefore have sex-specific prognostic value in this population.