Comparison of major definitions of sarcopenia based on the skeletal muscle index in patients with urothelial carcinoma.

For the past decade, sarcopenia has been actively investigated in various cancers, including urothelial carcinoma (UC). Although skeletal muscle index (SMI) is the main parameter used to evaluate sarcopenia in oncology, the optimal definition of SMI-based sarcopenia is not entirely standardized. We recently highlighted the potential limitations of current definitions of SMI-based sarcopenia in another journal. In this study, we reviewed studies that assessed sarcopenia in UC patients. We then performed a comparative validation of three major SMI-based definitions of sarcopenia, including Prado's, the international and Martin's definitions in metastatic UC patients. We believe that the standardization of the sarcopenia definition is an urgent issue in oncology, and this paper discusses a possible new direction to address this issue.