Prognostic Value of Pretreatment Skeletal Muscle Mass Index in Esophageal Cancer Patients: A Meta-Analysis

The prognostic role of pretreatment skeletal muscle mass index (SMI) has been verified in several types of cancers. However, it remains unclear whether pretreatment SMI is a valuable prognostic indicator in esophageal cancer. The aim of the present study was to identify the prognostic value of pretreatment SMI in esophageal cancer. PubMed, EMBASE and Web of Science databases were searched for relevant studies up to November 10, 2021. The hazard ratios (HRs) with 95% confidence intervals (CIs) were combined to assess the association of pretreatment SMI with the overall survival (OS) and disease-free survival (DFS) of esophageal cancer patients. In total, 17 studies involving 2441 patients were included in this meta-analysis. The pooled results demonstrated that a lower SMI was significantly associated with poorer OS (HR = 1.18, 95% CI: 1.09–1.27, P < 0.001) and DFS (HR = 1.78, 95% CI: 1.10–2.88, P = 0.019). In addition, subgroup analysis based on treatment (surgery vs. nonsurgery), tumor type (squamous cell carcinoma vs. adenocarcinoma) and cutoff value of SMI showed similar results. The present findings demonstrated that pretreatment SMI is an independent prognostic indicator for esophageal cancer patients, and patients with a lower pretreatment SMI are more likely to have a worse prognosis. However, additional prospective high-quality studies are needed to verify the above findings.