Intermuscular adipose tissue as a prognostic biomarker for overall survival in colorectal cancer

Abstract

Background: The prognostic value of intermuscular adipose tissue (IMAT) in patients with colorectal cancer (CRC) depends on both the anatomical site selected for CT imaging and the analytical technique employed. This study assessed the clinical significance of IMAT-related parameters in patients with CRC. Methods: This retrospective cohort study included stage I-III CRC patients who underwent surgery at a single tertiary center between 2005 and 2014. CT scans at the L3 level measured skeletal muscle and IMAT area and radiodensity. Sex-specific cutoffs for IMAT index (IMAI: IMAT area/height2) and IMAT radiodensity (IMAD) were defined using the X-tile program. Patients were further categorized into IMAT-combined groups (G1, G2, G3, and G4) according to the cutoff values of IMAI and IMAD. Survival was analyzed using Kaplan-Meier curves, log-rank tests, and Cox regression. Prognostic accuracy was evaluated with the concordance index (C-index). Results: Among 1080 patients (59.4% male), lower IMAI and IMAD correlated with better overall survival (OS). IMAT-combined groups were independent prognostic factors, with G2-G4 showing significantly better OS than G1. Patients were reclassified into two groups (G1 vs. G2-G4), termed the "IMAT model." The C-index demonstrated that incorporating the IMAT model yielded superior predictive performance compared to SMI alone (0.629 vs. 0.579; bootstrap mean difference = 0.050, 95% CI: 0.021-0.091) and SMD alone (0.617 vs. 0.590; bootstrap mean difference = 0.027, 95% CI: 0.009-0.052). Conclusions: The IMAT model is a significant independent prognostic factor for patients with CRC. Its use may enhance prognostic accuracy and support personalized treatment planning.