Early Changes in Volumetric Body Composition Parameters Predict Survival Outcomes in Patients with Metastatic Renal Cell Carcinoma Treated with Targeted Therapy

<b>Background/Objectives</b>: The precise role of volumetric body composition (VBC) parameters, visceral adipose tissue index (VATI), subcutaneous adipose tissue index (SATI), and skeletal muscle index (SMI) on the survival of metastatic renal cell carcinoma (mRCC) is not fully elucidated. Herein, the present study investigated the clinical significance of baseline VBC parameters and their changes after 3-4 months from treatment initiation in patients with mRCC treated with first-line targeted therapy. <b>Methods</b>: A total of 108 patients were enrolled. VBC parameters were depicted from computerized tomography (CT) images at the third lumbar vertebra level. Kaplan-Meier curves were used to estimate survival probability, and the differences between prognostic subgroups were compared with the log-rank test. The association of baseline VBC variables and their change values (First CT value minus baseline CT value) with progression-free survival (PFS) and overall survival (OS) was evaluated in univariate and multivariate analyses. <b>Results</b>: The median PFS and OS of the whole patients were 11 and 46 months, respectively. Patients with increased VATI and SATI change values had poorer OS than those with decreased values. However, patients with higher SMI change values had superior OS than those with lower values. Among VBC variables, the independent predictors of worse OS were high VATI change (HR 5.10, <i>p</i> = 0.001) and low SMI change values (HR 2.66, <i>p</i> = 0.007), in addition to International Metastatic Renal Cell Carcinoma Database Consortium prognostic stratification (<i>p</i> = 0.001). <b>Conclusions</b>: Our findings showed that high VATI and low SMI changes were associated with worse OS in mRCC patients treated with first-line targeted therapy.