Is There an Optimal Definition for a Positive Circumferential Resection Margin in Locally Advanced Esophageal Cancer?

Background: Two definitions of a positive circumferential resection margin (CRM) in esophageal cancer coexist: one by the College of American Pathologists (CAP) (CRM = 0 mm) and another by the Royal College of Pathologists (RCP) (CRM ≤ 1 mm). This study aimed to evaluate the prognostic value of both definitions in esophageal cancer and to identify a new cutoff value for the CRM to predict survival. Methods: Patients who underwent curative esophageal resection for locally advanced (≥ pT3) adenocarcinoma or squamous cell carcinoma were selected from 2007 to 2016. The CRM was reassessed using an ocular micrometer. Overall survival (OS) and disease-free survival were estimated with uni- and multivariate analyses. Results: The study enrolled 283 patients: 48 with a positive CRM according to the CAP definition and 171 with a positive CRM according to the RCP definition. In the multivariate analysis, a positive CRM according to both definitions was significantly associated with a poor OS (CAP: hazard ratio [HR], 2.26, p < 0.001; RCP: HR, 1.42, p = 0.035). A CRM of 0 mm was predictive of a worse OS and DFS than a CRM of 1 mm or less (p < 0.0001), whereas no significant difference was found between a CRM greater than 1 mm and a CRM of 1 mm or less, indicating that the CAP definition was more accurate for predicting prognosis and recurrence. New cutoff CRM values of 100 µm in squamous cell carcinoma and 200 µm in adenocarcinoma were optimal for predicting OS. Conclusion: The CAP definition was more accurate for predicting prognosis and recurrence. The study identified a new cutoff value of CRM according to histologic type. [ABSTRACT FROM AUTHOR]