Evaluating the influence of sarcopenia and myosteatosis on clinical outcomes in gastric cancer patients undergoing immune checkpoint inhibitor therapy

Objective: The primary objective of this retrospective study was to assess the influence of sarcopenia and myosteatosis on clinical outcomes in patients with gastric cancer (GC) who underwent treatment with Immune Checkpoint Inhibitors (ICIs). Methods: : In this retrospective analysis, the study cohort comprised patients who had received immunotherapy for gastric cancer. Sarcopenia, evaluated at the L3 vertebral level, was determined based on pre-treatment CT scans using the Receiver Operating Characteristic (ROC) analysis to establish the optimal skeletal muscle index cut-off value. Myosteatosis was defined using the mean Skeletal Muscle Density (SMD), with a threshold value of <41 Hounsfield Units (HU) for patients with a Body Mass Index (BMI) < 25 kg/m² and <33 HU for patients with a BMI ≥ 25 kg/m². Statistical analyses, including the log-rank test and the Cox proportional hazard model, were employed to compare both Progression-Free Survival (PFS) and Overall Survival (OS). Nomograms predicting PFS and OS were developed based on the results of multivariate analyses. Results: : The study encompassed a total of 124 patients who had undergone ICIs for GC, among which 27.4% exhibited sarcopenia, and 29.8% displayed myosteatosis. Patients with sarcopenia or myosteatosis exhibited significantly reduced PFS and OS compared to those without these conditions. Furthermore, both sarcopenia and myosteatosis emerged as independent prognostic factors for PFS and OS in GC patients receiving ICIs. The prediction models for PFS and OS demonstrated C-indexes of 0.757 and 0.777, respectively. Conclusion: The findings of this study affirm the utility of sarcopenia and myosteatosis as reliable biomarkers for forecasting clinical outcomes in patients with gastric cancer who are undergoing treatment with ICIs.