The prognostic significance of sarcopenia in patients treated with definitive radiotherapy: A systematic review.

Sarcopenia describes the degenerative loss of muscle mass and strength, and is emerging as a pan-cancer prognostic biomarker. It is linked with increased treatment toxicity, decreased survival and significant healthcare financial burden. Systematic analyses of sarcopenia studies have focused on outcomes in patients treated surgically or with systemic therapies. There are few publications concerning patients treated with radiotherapy. This manuscript presents a pan-cancer systematic review of the association between sarcopenia and survival outcomes in patients treated with definitive (chemo-)radiotherapy. A literature search was performed, with 26 studies identified, including a total of 5,784 patients. The prognostic significance of sarcopenia was mixed. This may reflect lack of consensus in methods used to measure skeletal muscle mass and define sarcopenia. Many papers analyse small samples and present sarcopenia cutoffs optimised on the local population, which may not generalise to external populations. Recent advances in artificial intelligence allow for automatic measurement of body composition by segmenting the muscle compartment on routinely collected imaging. This provides opportunity for standardisation of measurement methods and definitions across populations. Adopting sarcopenia diagnosis into clinical workflows could reduce futile treatments and associated financial burden, by reducing treatment toxicities, and improving treatment completion, patient survival, and quality-of-life after cancer.