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

Background: The 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 Methods: We 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 cm(2)/m(2) (men), < 39 cm(2)/m(2) (women); others: lowest sex-specific quartiles. Predictive values for cancer-specific survival (CSS) were assessed using the Cox proportional hazards regression model.
Results: Sixty-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.
Conclusion: Evaluation 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.
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