Impact of Body Mass Index on the Prognosis of Patients Undergoing Nephrectomy for Non-metastatic Clear Cell Renal Cell Carcinoma

초록

Introduction: A significant association of a high body mass index (BMI) with an increased incidence for renal cell carcinoma (RCC) has been described in several studies. However, the information on the association between BMI and prognosis in patients with RCC is limited and remains controversial. In this study, we investigated the association of BMI with prognosis in patients undergoing nephrectomy for non-metastatic clear cell RCC. Materials & Methods: Between January 1995 and May 2005, 1,179 radical or partial nephrectomy for non-metastatic RCC was performed in 11 hospitals in Korea, among which 993 (84.2%) were clear cell RCC. BMI data were available for analysis in 977 patients. The mean age at surgery was 55.2 (17-84) years and the percentage of male was 70.0%. Patients were grouped according to BMI based on the Asia-Pacific criteria for obesity as underweight (less than 18.5 kg/m2), normal (18.5 to 22.9 kg/m2), overweight (23 to 24.9 kg/m2), and obese (25 kg/m2 or more). Thirty-four patients (3.5%) were categorized as underweight, 340 (34.8%) as normal, 248 (25.4%) as overweight, and 355 (36.3%) as obese. Underweight group was excluded from the analysis. Demographic and clinicopathological parameters of three BMI groups were analyzed. Results: The three BMI groups were significantly different in presenting symptoms (p=0.046), but not different in age, sex, tumor size, T stage and grade. On univariate analyses, presenting symptoms, tumor size, T stage and grade were significant prognostic factors for overall, cancer-specific and disease-free survival. BMI of 23 kg/m2 or more compared to less than 23 kg/m2 was identified as significant prognostic factor for disease-free survival, but not for overall and cancer-specific survival. On multivariate analyses, tumor size, T stage and grade were independent prognostic factors for overall, cancer-specific and disease-free survival, but BMI was not an independent factor. Conclusions: Our findings suggest that among p