Impact of positive tumor-informed margin and TP53 mutations on surgical outcomes in esophageal squamous cell carcinoma.

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e16024 Background: The complete removal of esophageal squamous cell carcinoma (ESCC) with clear margins (R0 resection) is pivotal for patient prognosis. However, it is limited by the potential inaccuracies of conventional histopathology. Next-generation sequencing (NGS) for minimal residual disease (MRD) detection might improve the prediction of postoperative outcomes. Methods: The study cohort included a total of 48 operable ESCC patients, from whom resected esophageal tumors, resection margins, and normal tissues were collected and profiled by a 425-gene panel. Comparisons of mutational features were conducted across various tissue types, and their associations with disease-free survival (DFS) were explored. Results: Mutations were detected in 81.8% (27/33) of normal tissues, 95.8% (46/48) of tumors, and 50.0% (24/48) of resection margins. In general, genetic alterations in resection margins closely resembled those in tumor tissues, but were distinct from normal tissues. Both tumor and margin samples showed higher variant allele frequencies (VAFs) and fewer mutations per patient than normal samples ( p < 0.0001). Moreover, eight patients exhibited identical mutations in paired margin and tumor samples. Notably, one patient out of eight with the same TP53 p.T175H mutation across all sample types exhibited the shortest DFS of only two months. Mutations in TP53 and NOTCH1 were the most common, displaying unique mutational patterns among different sample types. While NOTCH1 mutations were detected more frequently in normal tissues ( p = 0.001), TP53 mutations were enriched in tumors ( p = 0.04). Furthermore, normal tissues exhibited a distinct pattern of mutation sites for TP53 and NOTCH1 compared to those observed in tumor or margin tissues. We characterized tumor-informed margin (TiM) by the presence of identical mutations in both tumor and adjacent margins. The positive TiM status was associated with a shorter DFS, particularly when considering TP53 mutations alone ( p = 0.022) or excluding NOTCH1 mutations ( p = 0.031). Conclusions: A positive TiM status with TP53 mutations is a promising biomarker indicating poor surgical outcomes in ESCC. Mutations within NOTCH1 are common but showed no association with DFS. These findings provide novel insights into the feasibility of genetic profiling of resection margins to facilitate optimizing postoperative therapeutic regimens for ESCC.