ESTRO 2025 - Abstract Book

S1187

Clinical – Lower GI

ESTRO 2025

Results: The habitat imaging framework successfully stratified patients into two distinct imaging subtypes with significantly different DFS outcomes ( P = .014 for discovery and 0.012 for validation cohort, Fig. 2). The high-risk imaging subtype demonstrated significantly worse DFS compared to the low-risk subtype (HR = 1.705, 95% CI: 1.118 - 2.601) in discovery cohort. This prognostic value remained significant after adjusting for conventional clinicopathological factors (adjusted HR = 0.410, 95% CI: 0.190-0.880, P = .022 in discovery cohort, and 1.670, 95% CI: 1.08-2.57, P = .02 in validation cohort), including age, sex, clinical T and N stage. The imaging subtypes showed robust performance in both discovery (C-index: 0.604; 95% CI: 0.520-0.691; n = 488) and validation cohorts (C-index: 0.572; 95% CI: 0.529 0.615; n = 136), providing independent prognostic information beyond traditional risk factors.

Conclusion: Our study establishes a novel MRI-based habitat imaging framework focusing on the mesorectum that effectively stratifies LARC patients into distinct prognostic groups based on pre-treatment imaging features. These imaging subtypes provide independent prognostic information for DFS prediction in patients undergoing neoadjuvant chemoradiotherapy and surgery. This approach could potentially aid in personalized treatment planning and risk stratification for LARC patients.