Changes in Components of Sarcopenia Diagnostic Criteria Throughout the Surgical Treatment of Oesophagogastric Cancer Surgery: A Prospective Longitudinal Study

Introduction: Low skeletal muscle is prevalent and associated with poorer outcomes after oesophagogastric (OG) cancer surgery. However, sarcopenia, including strength and function, is less commonly assessed. Therefore, we aimed to describe the prevalence of sarcopenia and changes in diagnostic criteria within 1 year of OG cancer surgery. Methods: This prospective observational study included OG cancer surgery patients from 2018 to 2021. Body composition was assessed using computed tomography (CT) and bioimpedance spectroscopy (BIS). Low CT-defined skeletal muscle index (SMI) and myosteatosis were defined using published thresholds. Low fat-free mass index (FFMI) cut points were < 17 kg/m² for men and < 15 kg/m² for women. Hand grip strength (HGS, kg) and 6-metre walk test (metres/second) measured strength and function, respectively. Sarcopenia, defined using the European Working Group on Sarcopenia in Older People 2019 criteria, was assessed preoperatively, 2-, 6- and 12-weeks post-discharge and 6 and 12 months postoperatively. Results: Forty-eight patients, predominantly male (63%) with a mean (SD) age of 64 (10.1) years, were included preoperatively, and 25 patients at 1 year. Low SMI (50%) and myosteatosis (50%) were prevalent preoperatively. Fewer patients had low FFMI (6%), low HGS (17%), and low walk speed (6%). The prevalence of Sarcopenia-CT was 15% preoperatively and 12% at 1-year (p = 0.32), and sarcopenia-BIS was 2% preoperatively and 3% at 1-year (p = 0.60). Conclusions: Despite a high prevalence of low SMI and myosteatosis, sarcopenia was less common. Low muscle mass, with adequate strength and function, is a prominent feature. Given the negative outcomes of low SMI, muscle assessment remains a valuable and clinically meaningful measure.