Objective: The aim of the current study was to examine the impact of preoperative body mass index (BMI) in Korean patients with surgically treated renal cell carcinoma (RCC).
Methods: From 1994 to 2008, a total of 1,487 patients underwent nephrectomy for RCC. All patients were classified into three groups according to Asian BMI classification by Asia Cohort Consortium: <18.5, 18.5 to <25, and 25 kg/m(2) or greater group, which represents the underweight (n = 42, 2.8%), normal (n = 833, 56.0%), and obesity (n = 612, 41.2%) group, respectively. Survival analyses and predictive factors for cancer-specific survival among the three groups were evaluated. Subgroup survival analysis of organ-confined and advanced disease was performed.
Results: An overall median follow-up was 54.8 months. Mean ± SE estimated cancer-specific survival in all patients at 5 and 10 years was 88.0 ± 1.0% and 81.4 ± 1.4%, respectively. In the multivariate model after adjusting preoperative and postoperative variables, the underweight group had a significantly worse prognosis than the normal group (hazard ratio (HR): 2.17, 95% confidence interval (95% CI): 1.16-4.08, p = 0.016), meanwhile the obesity group was associated with improved survival (HR: 0.66, 95% CI: 0.45-0.96, p = 0.032). In the subgroup analysis of advanced RCC, obesity was associated with better prognosis than the normal group after applying multivariate analysis (p = 0.001).
Conclusions: Preoperative underweight could be a new independent factor to predict unfavorable cancer-specific survival in Korean patients with RCC treated by surgery. Moreover, obesity was verified to be associated with superior cancer-specific survival.