Prognostic Value of Body Mass Index According to Histologic Subtype in Nonmetastatic Renal Cell Carcinoma: A Large Cohort Analysis

In 2769 patients with nonmetastatic renal cell carcinoma (RCC), the prognostic value of body mass index (BMI) according to histologic subtype was assessed. Increased BMI was associated with increased survival in clear cell RCC and decreased survival in chromophobe RCC, and not associated in papillary RCC. The association between BMI and RCC prognosis may differ by histologic subtype. Objective: The objective of our study was to assess the prognostic value of body mass index (BMI) according to histologic subtype in nonmetastatic renal cell carcinoma (RCC), based on a large multicenter experience. Methods: A total of 2769 patients with nonmetastatic RCC at the time of surgery were enrolled from 5 Korean institutions between 1999 and 2011. BMI was used as a continuous variable and was categorized according to the World Health Organization recommendation for Asians into normal weight (≥ 18.5 and < 23 kg/m²) and overweight and obese (≥ 23 kg/m²). Results: In patients with clear cell variant, increased BMI was associated with higher recurrence-free survival (RFS) or cancer-specific survival (CSS) rates by multivariate analyses (hazard ratio [HR] of RFS, 0.940; P =.007; HR of CSS, 0.875; P <.001). On the other hand, increased BMI in patients with chromophobe variant was associated with lower RFS or CSS rates, unlike in patients with clear cell variant (HR of RFS, 1.317, P =.011; HR of CSS, 1.320; P =.031). In patients with papillary variant, BMI was not associated with RFS or CSS (P >.05 for each). Conclusions: Our results showed that increased BMI was a favorable prognostic factor in patients with clear cell variant. However, increased BMI was a poor prognostic factor in patients with chromophobe variant and was not associated with prognosis in those with papillary variant. Our study suggests that the association between BMI and RCC prognosis may differ by histologic subtype.