Skeletal muscle gauge: A superior predictor of neoadjuvant chemoimmunotherapy efficacy in locally advanced gastric cancer.

Background: Muscle parameters are closely related to the efficacy of neoadjuvant therapy, and this study aims to analyze the predictive value of a novel muscle parameter index (skeletal muscle gauge, SMG) for the efficacy of neoadjuvant chemotherapy and immunotherapy(NCI) in locally advanced gastric cancer(LAGC).

Method: A retrospective analysis was conducted on the clinical pathological data and abdominal CT images of patients with LAGC who received NCI at the Second Affiliated Hospital of Nanchang University from September 2020 to December 2023. The body composition, including skeletal muscle index (SMI), skeletal muscle radiation attenuation (SMRA), and the new skeletal muscle parameter- SMG (obtained by multiplying SMI and SMRA), was calculated using the SliceOmatic software before and after NCI. The relationships between the three skeletal muscle parameters and the NCI efficacy and postoperative complications were analyzed and compared.

Results: A total of 162 patients were included in this study,Before neoadjuvant, the median SMI was 38.1(34.2-44.3)cm/m, SMRA was 44.7(41.1-48.4)HU, and SMG was 1776(1449-1979).Multivariate logistic analysis showed that cN stage (OR: 5.75, 95% CI: 3.21-11.52, p=0.008) and SMG(OR: 0.99, 95% CI: 0.96-0.99, p=0.001) were poor tumor regression (TRG 3 grade). SMI(OR:0.50, 95% CI: 0.29-0.88, p=0.016), SMRA(OR:0.58, 95% CI: 0.36-0.91, p=0.018) and SMG(OR:0.96, 95% CI: 0.96-0.99, p=0.001) are all protective factors for postoperative complications. ROC curve analysis showed that SMG was superior to SMI and SMRA in predicting tumor recession and postoperative complications.

Conclusion: The new skeletal muscle parameters showed better predictive performance in the efficacy of NCI for LAGC and are a promising evaluation indicator, but they still need to be verified by prospective studies with larger samples.