The Prognostic Effect of Sarcopenia in Solid Cancers Treated with Immunotherapy: A Systematic Review and...

Background: Sarcopenia, defined as the presence of low skeletal muscle mass, is highly prevalent in cancer patients and associated with adverse events and lower survival. Given the chronic inflammation associated with sarcopenia, it is especially relevant in patients receiving immunotherapy. The current research is limited to small sample sizes and single cancer types leaving the overall effect of sarcopenia unclear. This review and meta-analysis examined the prognostic effect of sarcopenia in cancer patients treated with immunotherapy. Methods: A systematic review was conducted using EMBASE, MEDLINE, Cochrane, and Scopus. Studies were included if they investigated the association of baseline low skeletal muscle mass, as measured on CT or MRI and normalised for height, and survival in patients with solid tumours treated with immunotherapy. A meta-analysis of hazard ratios (HR) was performed using a random effects model for overall survival (OS) and progression-free survival (PFS). Results: In total, 48 studies were included in this review, of which 42 were included in the meta-analysis. The prevalence of sarcopenia ranged between 19.5% and 83.6%. The meta-analysis showed an overall prognostic effect of sarcopenia for OS and PFS (HR = 1.58; 95% CI 1.35-1.85; p < 0.0001 and HR = 1.50; 95% CI 1.30-1.72; p < 0.001, respectively). High heterogeneity was present between the included studies, which could possibly be explained by the differences in sarcopenia definition, cutoff values, and measurement techniques. Conclusions: Sarcopenia is a significant adverse prognostic factor for both OS and PFS in patients with solid tumours treated with immunotherapy across cancer types. Further research into the underlying mechanism of sarcopenia and its relation to the immune response and survival is needed. Prospective intervention studies are required to establish the care needed, such as nutrition and exercise, to improve the prognosis of sarcopenic patients.