Influence of body mass index on oncological outcomes in patients with upper urinary tract urothelial carcinoma treated with radical nephroureterectomy

Objective: To investigate the association between body mass index and oncological outcomes in Chinese patients who had undergone radical nephroureterectomy for upper urinary tract urothelial carcinoma. Methods: Between August 1998 and October 2009, 236 consecutive Chinese patients underwent radical nephroureterectomy for upper urinary tract urothelial carcinoma at Sun Yat-sen University Cancer Center (Guangzhou, China). Body mass index data were available for 230 (97.5%) of these patients. All 230 patients were classified into three groups according to the body mass index criteria for Asians, issued by the Asia Cohort Consortium: underweight, body mass index <18.5 kg/m(2) (n = 21, 9.1%); normal weight, body mass index >= 18.5 and <25 kg/m(2) (n = 151, 65.7%); and obesity, body mass index >= 25 kg/m(2), (n = 58, 25.2%). Spearman's rank correlation, Kaplan-Meier plots and Cox proportional hazards regression model were used to analyze the data. Results: Being underweight was significantly associated with lymph node metastasis (P = 0.017) and Eastern Cooperative Oncology Group performance status (P = 0.003). Univariate analysis showed recurrence-free survival and cancer-specific survival were significantly worse in underweight patients than in patients with normal weight or obese patients. After adjustments for other clinicopathological variables, multivariate analysis confirmed that recurrence-free survival and cancer-specific survival were significantly worse in underweight patients than in patients with normal weight or obese patients (recurrence-free survival P = 0.014, cancer-specific survival P = 0.015). Conclusions: Preoperative underweight is an independent predictor of unfavorable recurrence-free survival and cancer-specific survival in Chinese patients with upper urinary tract urothelial carcinoma treated by radical nephroureterectomy, whereas obesity is associated with superior recurrence-free survival and cancer-specific survival. Further studies, including a multi-institutional, prospective, Asian cohort study, are required to confirm these findings.