Sarcopenia Evaluated Using the Skeletal Muscle Index Is a Significant Prognostic Factor for Metastatic Urothelial Carcinoma

BackgroundThe purpose of the study was to evaluate the prognostic value of sarcopenia (muscle loss) in patients with metastatic urothelial carcinoma (UC), in a comparison of several methods of computed tomography (CT)-based evaluation of sarcopenia.Patients and MethodsWe retrospectively reviewed 100 patients with metastatic UC who underwent first-line systemic chemotherapy between 2003 and 2014. Sarcopenia was assessed by the following CT-based methods: skeletal muscle index (SMI), total psoas area (TPA), axial and/or transversal psoas thickness at the level of the third lumbar vertebrae, and axial and/or transversal psoas thickness at the umbilicus level (U-TPT). All parameters were standardized by either height or height squared. Cutoff points were SMI: < 55 cm2/m2 (men), < 39 cm2/m2 (women); others: lowest sex-specific quartiles. Predictive values for cancer-specific survival (CSS) were assessed using the Cox proportional hazards regression model.ResultsSixty-four patients met the eligibility criterion for analysis: those who underwent CT scans within 30 days before chemotherapy. Of them, 52 (81%) died of UC during the follow-up, with a median survival time of 13 months. Univariate analysis associated decreased SMI, TPA, and U-TPT with poor CSS. Multivariate analysis together with other pretreatment clinicopathologic parameters showed decreased SMI to be an independent predictor of poor CSS.ConclusionEvaluation using SMI showed sarcopenia was an independent predictor of poor prognosis for patients with metastatic UC who underwent first-line systemic chemotherapy. Our results might improve stratification of patients and help optimize evaluation of sarcopenia.