Prognostic Significance of Sarcopenia in Patients with Metastatic Renal Cell Carcinoma

PURPOSE: Sarcopenia, a novel concept reflecting the degenerative loss of skeletal muscle mass, is a critical physiological change during the development of cancer cachexia. We retrospectively investigated the prognostic role of sarcopenia in patients with metastatic renal cell carcinoma. MATERIALS AND METHODS: Skeletal muscle index was calculated using computerized tomography performed at the diagnosis of metastatic renal cell carcinoma. Sarcopenia was defined as skeletal muscle index less than 43 cm(2)/m(2) for males with a body mass index less than 25 kg/m(2), less than 53 cm(2)/m(2) for males with a body mass index 25 kg/m(2) or greater, and less than 41 cm(2)/m(2) for females. The relationship between sarcopenia and overall survival was assessed in 92 patients with metastatic renal cell carcinoma using Cox proportional hazards models. The predictive accuracy of these models was evaluated using the c-index. RESULTS: A total of 63 (68%) patients were classified as having sarcopenia and 52 (57%) died (median overall survival 27 months) during followup (median 19 months). A multivariate analysis identified sarcopenia as a significant and independent predictor of overall survival (HR 2.58, p = 0.015), along with prior nephrectomy (p <0.001), number of metastatic sites (p = 0.017), corrected calcium (p = 0.026) and lactate dehydrogenase (p = 0.006). The 3-year overall survival rates were 31% and 73% for sarcopenic and nonsarcopenic cases, respectively (p <0.001). The integration of sarcopenia into the Memorial Sloan Kettering Cancer Center risk model improved the c-index from 0.726 to 0.758 (addition of sarcopenia to the original model) and 0.755 (substitution of sarcopenia for Karnofsky performance status). CONCLUSIONS: Sarcopenia is a significant prognostic factor in metastatic renal cell carcinoma.