LAUSR

e16047 Background: Low skeletal muscle mass and density are independent predictors of clinical outcomes in multiple gastrointestinal cancers. However, its effect on the long-term survival of locally advanced esophageal cancer patients undergoing radical radiotherapy is still unclear. Methods: Patients with stage II-III esophageal cancer undergoing radical radiotherapy, enrolled in a observational cohort study, were included. Skeletal muscle mass and density were measured on CT. Patients with high and low skeletal muscle mass and density were compared regarding overall survival (OS). Results: In total, 165 patients (75.8% males, median age 63) were included, from March 2012 to September 2017. Before radiotherapy, 26.7% patients had low skeletal muscle mass and 23.0% patients had low skeletal muscle density. After radiotherapy, 40.6% patients had low skeletal muscle mass and 30.3% patients had low skeletal muscle density.The median OS of high skeletal muscle mass and density group was significantly higher than that of low skeletal muscle mass and density group before radiotherapy (28.7 months vs 28.2 months, p = 0.041; 29.6 months vs 16.9 months, p = 0.025). The median OS of high skeletal muscle mass and density group was also significantly higher than that of low skeletal muscle mass and density group after radiotherapy (30.3 months vs 20.3 months, P = 0.012; 29.6 months vs 17.2 months, p = 0.018). Conclusions: Low skeletal muscle mass and density are associated with long-term outcome in patients undergoing radical radiotherapy. It is suggested that oncologists should pay more attention to the management of muscle mass and density of patients with esophageal cancer undergoing radiotherapy in order to improve their nutritional status and long-term survival.