P1.190. Residual Disease Subgroups and Survival After Trimodality Therapy for Esophageal Squamous Cell Carcinoma - Observational Study

Abstract

Esophageal Cancer: Surgical Treatment of Esophageal Cancer – early outcomes and complications For locally advanced oesophageal squamous cell carcinoma (ESCC) managed with trimodality therapy, the prognostic significance of different patterns of residual disease within the non-pathological complete response (non-pCR) population remains incompletely defined. This study applied a four-group pathological response classification to evaluate whether the anatomical distribution of residual disease — at the primary site, at regional lymph nodes, or at both — differentially determines disease-free and overall survival. This retrospective, observational cohort study included 187 consecutive patients with ESCC who underwent neoadjuvant concurrent chemoradiotherapy (nCRT) followed by curative-intent oesophagectomy India, between 2021 and 2026. Patients were classified into four mutually exclusive groups: pCR+ (ypT0N0; n=91, 48.7%); Local Residual Disease (LRD: ypT≥1, ypN0; n=53, 28.3%); Nodal Residual Only (NRO: ypT0, ypN+; n=13, 7.0%); and combined Local and Nodal Residual Disease (LRD+NRO: ypT≥1, ypN+; n=30, 16.0%). Primary endpoints were disease-free survival (DFS) and overall survival (OS). Groups were compared by Kaplan–Meier analysis with Bonferroni-corrected pairwise log-rank tests. Independent prognostic determinants were identified by multivariable Cox proportional hazards regression with LRD+NRO as the reference category. The four groups differed significantly in observed survival at last follow-up (p<0.001): alive rates were 79.5% (pCR+), 76.1% (LRD), 100% (NRO; exploratory, n=13), and 47.8% (LRD+NRO). Estimated three-year OS was approximately 80%, 72%, 85%, and 42%, respectively. On multivariable analysis, pCR+ was independently associated with significantly better DFS (adjusted hazard ratio [aHR] 0.38, 95% CI 0.21–0.68; p<0.001) and OS (aHR 0.41; p<0.001) versus LRD+NRO. LRD was also independently associated with improved DFS versus LRD+NRO (aHR 0.55, 95% CI 0.30–1.00; p=0.049). R1 resection margin was independently associated with worse DFS (aHR 1.83; p=0.036). The NRO result was non-significant (aHR 0.62; p=0.32), likely reflecting limited power (n=13). Combined local and nodal residual disease (LRD+NRO) confers the worst prognosis following trimodality therapy for ESCC. The four-group classification provides granular prognostic stratification beyond binary pCR assessment and has direct implications for adjuvant therapy planning and post-operative surveillance intensity. Prospective validation in larger cohorts is warranted, with particular focus on the NRO subgroup.