ESTRO 2025 - Abstract Book

S3811

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2025

The cutoff value distinguishing high-TIL high-TIL (TIL + ) and low-TIL (TIL – ) groups was optimised in a randomly selected hold-out cohort (N=128). This threshold was determined by maximising Youden’s index in receiver operating characteristic (ROC) analysis for predicting three-year vital status. The remaining cohort (N = 300) was used for univariate and multivariate analysis. Overall survival (OS) was evaluated by Kaplan-Meier estimation, with log-rank tests employed to compare survival curves between subgroups. Hazard ratios (HR) and 95% confidence intervals (CI) were given by a Cox proportional hazards (PH) model. Results: The optimal cutoff value of 1,616 stratified 189/300 (63%) patients as TIL – and 111/300 (37%) patients as TIL + . TIL + patients have significantly longer OS (HR=0.31, 95%CI: 0.16-0.61, p<0.0005) ( Figure 1 ). In the multivariate Cox PH model ( Figure 2 ), the TIL status remained a significant prognostic factor (HR=0.33, 95%CI: 0.16-0.67, p=0.002), independent of age (>60 vs. ≤60 years), AJCC stage (I–III vs. IV) and pathologic N stage (N0–N1 vs. N2).