LAUSR

Purpose Two methods are used to identify sarcopenia by calculating skeletal muscle area on computed tomography: the skeletal muscle index (SMI) and the psoas muscle index (PMI). Programmed death (PD)-1 inhibitors are helpful in treating metastatic renal cell carcinoma (mRCC). However, there remains insufficient information regarding a clear and easy-to-use biomarker for predicting the response to PD-1 inhibitors in patients with mRCC. Therefore, we investigated the influence of sarcopenia on clinical outcomes in patients with mRCC undergoing treatment with nivolumab. Materials and Methods This study evaluated 96 patients with RCC who received nivolumab. The SMI and PMI were calculated for each patient and normalized for stature by use of the following formulas: SMI (cm2/m2)=([skeletal muscle cross-sectional area at the level of L3]/[height]2) and PMI (cm2/m2) = ([left-right sum of the psoas muscle areas at the level of L3]/[height]2). The relationship of the clinical variables with progression-free survival and overall survival (OS) was examined using a Cox proportional hazards model. Results According to the SMI-based definition of sarcopenia, 74.0% of patients had sarcopenia. However, according to the PMI-based definition of sarcopenia, only 34.3% of patients were diagnosed with sarcopenia. Multivariate analysis identified sarcopenia based on PMI (hazard ratio [HR], 3.85; 95% confidence interval [CI], 2.04–7.26; p<0.001) and International Metastatic RCC Database Consortium poor risk status (HR, 1.90; 95% CI, 1.03–3.50; p=0.041) as significant and independent prognostic factors of OS. Conclusions PMI-based sarcopenia is a significant prognostic factor for OS in patients with RCC who receive nivolumab therapy.