L3-SMI as a predictor of overall survival in oesophageal cancer patients receiving PD-1 inhibitors combined with chemotherapy.

[BACKGROUND] Programmed death ligand-1 (PD-1), as an immunotherapy target, has been increasingly used in tumour therapies. But as reactions and outcomes to PD-1 inhibitors combined with chemotherapy vary individually, it is primarily important to identify an ideal indicator for predicting the therapeutic effectiveness in individual patients. Oesophageal cancer (EC) patients often have difficulty eating due to tumour blockage of the oesophagus, leading to malnutrition and muscle loss. Sarcopenia is one of the influencing factors for poor prognosis in tumour patients, but its role in PD-1 inhibitors combined with chemotherapy of EC patients is not fully clarified. In this study, we aimed to explore the prognostic significance of Sarcopenia measured by CT in EC patients treated with PD-1 antibody combined with chemotherapy.

[METHODS] The third lumbar skeletal muscle mass index (L3-SMI) was obtained from 83 EC patients before and 3 months after administration of PD-1 inhibitors combined with chemotherapy using conventional CT scans.

[RESULTS] Baseline L3-SMI and 3-month L3-SMI values were found not suitable for predicting the overall survival (OS) of EC patients ( = 0.32 &  = 0.055). Longitudinal change in L3-SMI (ΔL3-SMI) during PD-1 inhibitors combined with chemotherapy was identified as a relevant marker of OS in univariable analysis (HR: 0.98, 95% CI: 0.96-1.00,  = 0.042) and multivariable analysis (HR: 0.96, 95% CI: 0.93-0.99,  = 0.02). L3-SMI-positive patients generally had better OS ( = 0.041).

[CONCLUSION] Excessive muscle loss rather than muscle loss before and after administration of PD-1 inhibitors combined with chemotherapy is an important prognostic factor for therapeutic outcomes and OS in EC patients.