O100: A novel bedside assessment of skeletal muscle wasting predicts treatment-related toxicity prior to major surgery – The Muscle Ultrasound in Esophagogastric Cancer (MUSEC) study

Abstract Sarcopenia is an important prognosticator during treatment for Oesophagogastric (OG) cancer. Despite this, sarcopenia is not routinely measured in clinical practice due to resource availability. Ultrasound is emerging as a potential tool to quantify muscle mass and quality and might predict treatment-related complications. Skeletal muscle ultrasound has not been investigated in patients undergoing cancer treatment. Patients receiving treatment for OG cancer (chemotherapy plus surgery) were prospectively recruited. Ultrasound was performed at 4 time points during treatment. Primary outcome was a measurable change in skeletal muscle. Secondary outcome measures included correlation with gold-standard measures of muscle mass (CT skeletal muscle index (SMI)), and the association between sarcopenia on ultrasound and treatment-related complications. Fifty patients were recruited. Significant deterioration in quadriceps muscle thickness, cross sectional area, rectus femoris echointensity, and ultrasound sarcopenia index (USI) was observed during chemotherapy. USI showed moderate correlation with CT SMI (r = -.511, p=0.001) with ultrasound classifying more patients as sarcopenic (37% vs 18%, p=0.001), plus detecting a greater magnitude of muscle loss during chemotherapy (-20.2 ±18% vs -6.5 ±7.4%, p=<0.001). USI correlated better with physical function (1-minute sit to stand) compared to CT SMI (r .589, p=<0.001 versus r .149, p=0.169). Ultrasound-defined sarcopenia at baseline was associated with a higher incidence of dose limiting chemotoxicity and severe chemotoxicity but did not post-operative complications. Further validation studies are required, but bedside muscle ultrasound could provide an effective bedside assessment of muscle health and identifies a higher proportion of patients at risk of chemotoxicity prior to major surgery.