CT-based Extranodal Extension for Nodal Staging and Prognostic Stratification in Surgically Resectable Esophageal Squamous Cell Carcinoma.

Purpose To develop and validate a structured CT-based grading system for imaging-identified extranodal extension (iENE) and assess its diagnostic accuracy and prognostic significance in esophageal squamous cell carcinoma. Materials and Methods In this retrospective multicenter study, preoperative CT examinations in patients with esophageal squamous cell carcinoma treated at four tertiary hospitals between January 2017 and December 2023 were reviewed. CT features evaluated included indistinct nodal margins, coalescent nodal mass, invasive encasement, halo sign, and black ring sign. Radiologic-pathologic node-by-node correlation was performed in the development cohort to assess diagnostic performance. The validation cohort consisted of an independent, multicenter patient population and was used to evaluate the prognostic value of iENE at the patient level. Logistic regression and receiver operating characteristic analyses were used to assess diagnostic performance, while overall survival was evaluated using Kaplan-Meier and Cox regression analyses. Results A total of 912 patients with esophageal squamous cell carcinoma were included, with 95 patients (mean age, 62 years ± 8; 75 male patients) in the development cohort and 817 patients (mean age, 62 years ± 9; 619 male patients) in the validation cohort. Coalescent nodal mass, invasive encasement, and black ring sign at CT demonstrated 100% specificity for pathologic ENE. An iENE score of 2 or higher achieved optimal diagnostic performance (sensitivity, 82% [36 of 44]; specificity, 90% [250 of 279]; accuracy, 89% [286 of 323]). Patients with high-risk iENE (score ≥2) had worse overall survival than those with low-risk disease in both the development cohort (hazard ratio, 8.83; 95% CI: 3.30, 23.64; P < .001) and validation cohort (hazard ratio range, 26.02-39.48; all P < .001). On multivariable analysis, iENE remained an independent prognostic factor (adjusted hazard ratio, 8.72; 95% CI: 6.88, 11.05; P < .001). Conclusion The CT-based iENE grading system demonstrated high diagnostic performance and provided independent prognostic stratification in esophageal squamous cell carcinoma.