Low Skeletal Muscle as a Risk Factor for Worse Survival in Nonmetastatic Renal Cell Carcinoma with Venous Tumor Thrombus

Low muscle mass, defined as sarcopenia, is a risk factor for worse outcomes in malignancy, including renal cell carcinoma. This study evaluates the association of low muscle mass with mortality and complications in patients with renal cell carcinoma with venous tumor thrombus. Preoperative sarcopenia was associated with worse overall and cancer specific survival. Background: Renal cell carcinoma (RCC) with tumor thrombosis often requires nephrectomy and tumor thrombectomy. As an extensive and potentially morbid operation, patient preoperative functional reserve and body composition is an important consideration. Sarcopenia is a risk factor for increased postoperative complications, systemic therapy toxicity, and death solid organ tumors, including RCC. The influence of sarcopenia in RCC patients with tumor thrombus is not well defined. This study evaluates the prognostic ability of sarcopenia regarding surgical outcomes and complications in patients undergoing surgery for RCC with tumor thrombus. Methods: We retrospectively analyzed patients with nonmetastatic RCC and tumor thrombus undergoing radical nephrectomy and tumor thrombectomy. Skeletal muscle index (SMI; cm 2 /m 2 ) was measured on preoperative CT/MRI. Sarcopenia was defined using body mass index- and sex-stratified thresholds optimally fit via a receiver-operating characteristic analysis for survival. Associations between preoperative sarcopenia and overall (OS), cancer-specific survival (CSS), and 90-day major complications were determined using multivariable analysis. Results: 115 patients were analyzed, with median (IQR) age and body mass index of 69 (56-72) and 28.6 kg/m 2 (23.6-32.9), respectively. 96 (83.4%) of the cohort had ccRCC. Sarcopenia was associated with shorter median OS ( P = .0017) and CSS ( P = .0019) in Kaplan-Meier analysis. In multivariable analysis, preoperative sarcopenia was prognostic of shorter OS (HR = 3.38, 95% confidence interval [CI] 1.61-7.09) and CSS (HR = 5.15, 95% CI 1.46-18.18). Notably, 1 unit increases in SMI were associated with improved OS (HR = 0.97, 95% CI 0.94-0.999) but not CSS (HR = 0.95, 95% CI 0.90-1.01). No significant relationship between preoperative sarcopenia and 90-day major surgical complications was observed in this cohort (HR = 2.04, 95% CI 0.65-6.42). Conclusion: Preoperative sarcopenia was associated with decreased OS and CSS in patients surgically managed for nonmetastatic RCC and VTT, however, was not predictive of 90-day major postoperative complications. Body composition analysis has prognostic utility for patients with nonmetastatic RCC and venous tumor thrombus undergoing surgery.