Skeletal muscle radiodensity and cancer outcomes: A scoping review of the literature

Patients with cancer are more prone to experience myosteatosis than healthy individuals. The aim of this review was to summarize the methodologies applied for low skeletal muscle radiodensity (SMD) assessment in oncology patients, as well as to describe the major findings related to SMD and cancer outcomes. This scoping review included studies that were published until November 2020 in English, Portuguese, or Spanish; were performed in humans diagnosed with cancer, adult and/or elderly, of both sexes; investigated SMD through computed tomography of the region between the third and fifth lumbar vertebrae, considering at least two muscular groups; and evaluated clinical and/or surgical outcomes. Eighty-eight studies met the inclusion criteria (n = 37,583 patients). Survival was the most evaluated outcome. Most studies reported a significant association between low SMD and unfavorable outcomes. However, this relationship was not clear for survival, antineoplastic treatment, and surgical complications, potentially because of the unstandardized approaches for the assessment of SMD and inadequate study design. Future studies should address these issues to provide an in-depth understanding of the clinical relevance of SMD in cancer outcomes as well as how SMD is influenced by individuals and tumor-related characteristics in patients with cancer.