Prognostic value of psoas muscle index in metastatic renal cell carcinoma patients treated with anti-VEGF therapy

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BACKGROUND: We aimed to investigate the relationship between sarcopenia, which is defined by using psoas muscle index (PMI), and survival outcomes in patients with metastatic renal cell carcinoma (mRCC). METHODS: This is a retrospective descriptive study of mRCC treated with first-line anti-vascular endothelial growth factor (anti-VEGF) therapy. The prognostic significance of PMI for progression-free survival (PFS) and overall survival (OS) was evaluated by univariate and multivariate analyses. Additionally, the skeletal muscle index (SMI) was calculated and correlation analysis was performed between PMI and SMI. RESULTS: Eighty-eight patients with a median age of 60 years (interquartile range [IQR], 51-66) were included. Median PFS with first-line treatment was 6 (95% confidence interval [CI]: 2.9-9.03) months and median OS was 17 (95% CI: 10.6-23.03) months in all patients. Mean PMI was 5.71 (standard deviation [SD]: ±1.41) in women and 8.30 (SD: ±2.04) in men. Forty-seven (53.4%) patients according to PMI and 49 (55.6%) patients according to SMI were accepted as sarcopenic. The overall correlation between SMI and PMI was strong (rs = 0.73). PFS was numerically shorter in the low-PMI and low-SMI groups than the high-PMI and high-SMI groups, but it did not reach statistical significance. In univariate analyses, International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk score, anti-VEGF agent option, PMI, and SMI were significant prognostic factors for OS (P < 0.05 each). In multivariate analyses for OS, while IMDC score (P < 0.001) and PMI (P = 0.04) were significant independent prognostic factors according to multivariate analysis-1, IMDC score (P < 0.001) and SMI (P = 0.01) were significant independent prognostic factors according to multivariate analysis-2. CONCLUSIONS: Pretreatment PMI has a strong correlation with SMI and is an independent prognostic factor for OS in patients with mRCC.