Prognostic Impact of Postoperative Loss of Skeletal Muscle Mass in Patients Aged 70 Years or Older with Esophageal Cancer

Background: The number of patients with esophageal cancer aged ≥ 70 years with a poor prognosis is increasing. In general patients with esophageal cancer, postoperative loss of skeletal muscle mass (SMM) is a prognostic factor. This study was designed to investigate the prognostic impact of postoperative loss of SMM in patients aged ≥ 70 years with esophageal cancer. Methods: This study was a single-center, retrospective cohort study. Patients with esophageal cancer who underwent R0 esophagectomy between 2016 and 2020 were included. The percentage postoperative loss of skeletal muscle mass index (SMI%) was calculated using computed tomography images before and at 4 ± 2 months after surgery. Results: The number of subjects in the ≥ 70-year and < 70-year age groups was 166 and 218, respectively. The median SMI% was 5% in all patients; thus, 5% was defined as the cutoff point to define major loss of SMI. Major loss of SMI impacted 3-year overall survival (OS) in the ≥ 70-year age group, independent of age, sex, clinical stage, pathological T and N factors, Charlson comorbidity index, and length of hospital stay (adjusted hazard ratio [HR]: 4.400; 95% confidence interval: 1.202–16.105; P = 0.025). The adjusted HR of major loss of SMI in the ≥ 70-year age group was higher than in the < 70-year age group (adjusted HR: 4.400 vs. 2.388, respectively). Conclusions: Postoperative loss of SMI in patients with esophageal cancer aged ≥ 70 years more strongly impacted 3-year OS than in patients aged < 70 years.