Usefulness of skeletal muscle measurement by computed tomography in patients with esophageal cancer: changes in skeletal muscle mass due to neoadjuvant therapy and the effect on the prognosis

PurposeThis analysis was performed to clarify the usefulness of skeletal muscle measurements using computed tomography (CT) in patients with esophageal cancer and the effect of treatment-induced changes in the skeletal muscle mass on the prognosis.MethodsNinety-seven male patients who underwent thoracoscopic esophagectomy for esophageal squamous cell carcinoma were included in the study. The preoperative CT images were analyzed retrospectively.ResultsIn a survival analysis performed according to the preoperative data of skeletal muscle, the low-skeletal muscle index (l-SMI) group had a poorer outcome than the normal skeletal muscle index (n-SMI) group in terms of both the overall survival (OS) and the relapse-free survival (RFS) (OS: P < 0.01, RFS: P = 0.01). In the multivariate analysis for the OS, preoperative l-SMI was an independent predictor (hazard ratio: 3.68, 95% confidence interval 1.32-10.2, P = 0.01). In patients who underwent neoadjuvant therapy (NAT), the SMI was significantly reduced after NAT (P < 0.01). The preoperative skeletal muscle area on CT was strongly correlated with the results of a bioelectrical impedance analysis (BIA) (rho = 0.77, P < 0.01).ConclusionsA decreased preoperative skeletal muscle mass was associated with a poor outcome. In patients who underwent NAT, the SMI was significantly reduced after NAT. An analysis of the skeletal muscle mass using CT images was found to be useful for providing data that corresponded with BIA data.