Distinct Effect of Body Mass Index by Sex as a Prognostic Factor in Localized Renal Cell Carcinoma Treated with Nephrectomy ~ A Data from Multi-Institutional Study ~

PurposeWe assessed the prognostic value of body mass index (BMI) in Asian patients with localized RCC who underwent nephrectomy.Material and MethodsA total of 665 patients who underwent nephrectomy for localized RCC were enrolled in the present study and divided into the two BMI groups: i.e., BMI <25 in 463 (69.6%) and BMI >25 in 202 (30.4%) patients.ResultsThere were 482 (72.5%) and 183 (27.5%) patients in male and female, respectively. No significant difference in the distribution of sex was seen between BMI groups (p=0.498). Five-year cancer-specific survival (CSS) and recurrence-free survival (RFS) rate were significantly higher in higher BMI (97.1 and 91.1%) compared to lower BMI group (92.5 and 82.7%) (P = 0.007 for CSS, and p=0.019 for RFS). When stratified by sex, significantly longer CSS in higher BMI was confirmed in male (5-year CSS of 92.7% in BMI <25 and 98.1% in BMI >25, p=0.005), while there was no difference in CSS between BMI groups for female patients (5-year CSS of 91.9% in BMI <25 and 93.7% in BMI >25, p=0.738). Multivariate analysis revealed that BMI was an independent predictor for CSS in male (HR: 0.4, 95%CI: 0.14 - 0.95, p=0.036), but not in female (HR: 0.73, 95%CI: 0.20 – 2.10, p=0.576).ConclusionOur findings collected from the multi-institutional Japanese dataset demonstrated the longer survival in patients with higher BMI compared to lower BMI for non-metastatic RCC treated with nephrectomy. Intriguingly, this finding was restricted to males, but not to females.