Objectives: We aimed to evaluate the prognostic effect of low muscle mass (LMM), a marker of sarcopenia, in patients with metastatic RCC (mRCC) receiving nivolumab. Methods: We analyzed the data of 33 patients retrospectively. Total skeletal muscle index (SMI) and psoas muscle index (PMI) were measured using computed tomography scans at lumbar vertebra level. Low SMI was detected by use of population-specificcut-offs. Median PMI was calculated for men and women. Results: The median patient age was 61 (range: 55-65); 75.8% was male. Considering total skeletal muscle index, LMM was found in 10 (30.3%) patients. In the low SMI group, OS and PFS were significantly shorter compared to the normal SMI group (OS, median 6.76 vs. 56.26 months; PFS, median 5.13 vs. 39.41 months, respectively). In the patients having PMI lower than thesex-specific median PMI, OS and PFS were significantly shorter compared to the others (OS, 4.5 vs 61.82 months for male; OS 3.5 vs 64.83 months for female; PFS, 3.30 vs 53.65 months for male; PFS, 3 vs 49.91 months for female). In multivariate analysis, the only factor related to OS was ECOG-PS and to PFS was Fuhrman grade. Conclusion: In mRCC patients treated with nivolumab, those with low muscle mass had shorter OS and PFS. Future prospective randomized studies with higher number of participants are required to clarify the potential association of LMM with outcomes. Keywords: Sarcopenia, renal cell ccarcinoma, nivolumab
Corresponding Author: Seher Yildiz Tacar