Impact of early postoperative factors on changes in skeletal muscle mass after esophagectomy in older patients with esophageal cancer

Background Loss of skeletal muscle mass, measured by the skeletal muscle mass index (SMI), after esophagectomy negatively impacts prognosis. However, the information to develop novel supportive care options for preventing loss of skeletal muscle mass is limited. The purpose of this retrospective cohort study was to investigate the impact of early postoperative factors on change in SMI 4 months after curative esophagectomy in older patients with esophageal cancer. Methods This study included 113 subjects who underwent esophagectomy between 2015 and 2020. Preoperative and postoperative SMI (cm(2)/m(2)) were calculated from computed tomography images. The percentage change in SMI 4 months after surgery (SMI%) was calculated as follows: ([postoperative SMI - preoperative SMI] divided by preoperative SMI) x 100. Potential factors affecting percentage change of SMI after surgery were analyzed by multiple regression. Results The mean SMI% was - 5.6%. The percentage change (per 1%) in quadriceps muscle strength in the first month after surgery (standardized beta = 0.190, p = 0.048) impacted the SMI%, which was independent of age, sex, preoperative SMI, comorbidity, pathological stage, and neoadjuvant chemotherapy. Conclusion Quadriceps muscle weakness in the first month after esophagectomy impacted the SMI% in a dose-dependent relationship.