Differential effect of body mass index by gender on oncological outcomes in patients with renal cell carcinoma.

Objectives: To investigate the relationship between gender, body mass index (BMI), and prognosis in renal cell carcinoma (RCC) patients.
Materials and Methods: We retrospectively reviewed 1353 patients with RCC who underwent a partial or radical nephrectomy between 1988 and 2015. The association among sex, BMI, stage, grade, overall survival (OS), and recurrence-free survival (RFS) was analyzed.
Results: The median age of the patients was 59.4 ± 11.9 years. Female patients had proportionally lower grade tumors than male patients (Grade I-II in 75.5% vs. 69.3% in women and men, respectively, P = 0.022). There was no relationship between Fuhrman grade and BMI when substratified by gender (p > 0.05). There was a nonsignificant trend toward more localized disease in female patients (p = 0.058). There was no relationship between T stage and BMI when stratified by gender (p > 0.05). Patients with higher BMI had significantly better OS (p = 0.0004 and P = 0.0003) and RFS (P = 0.0209 and P =0.0082) whether broken out by lower 33 ^rd or 25 ^th percentile. Male patients with higher BMI had significantly better OS and RFS rates. However, there was no relationship between BMI and OS or RFS for female patients (P > 0.05). Multivariate analysis of the entire cohort demonstrated that a BMI in the lower quartile independently predicts OS (hazard ratio 1.604 [95% confidence interval: 1.07-2.408], P = 0.022) but not RFS (P > 0.05). When stratified by gender, there was no relationship between BMI and either OS or RFS (P > 0.05).
Conclusions: Increasing BMI was associated with RCC prognosis. However, the clinical association between BMI and oncologic outcomes may be different between men and women.
Competing Interests: None