The prognostic value of circumferential resection margin (CRM) definition and location in esophageal cancer: A 12-year cohort study

Background The definition of the circumferential resection margin (CRM) involvement for esophageal cancer varies between the Royal College of Pathologists (RCP) and College of American Pathologists (CAP). There are insufficient data regarding the prognostic relevance of different sites of involvement at the CRM. In this study, we examined the prognostic impacts of different CRM definitions and different radial margin locations. Methods This retrospective study included 449 patients who were treated by curative esophagectomy for esophageal or junctional cancers between 2010 and 2021. The distance of the closest tumour cells to the inked CRM was examined and site of CRM involvement was recorded. Patients with an involved longitudinal resection margin were excluded. Long-term follow up data were obtained from the hospital's electronic health records. Results Tumour cells at or within 1 mm from the CRM (CRM-RCP R1 <= 1 mm) was observed in 196 patients (43.7 %). CRM(<= 1 mm) was associated with poorer overall survival (OS) and disease-free survival (DFS) compared to CRM-R0, p-values <0.001 for both. Tumour cells at the CRM (CRM-CAP R1-0 mm) was observed in 61 patients (13.6 %). Patients with CRM-0mm had poorer OS and DFS compared to CRM <= 1 mm, p-values 0.039 and 0.013 respectively. Presence of tumour cells (CRM <= 1 mm) at multiple locations of the CRM was related to poorer survival compared to a single location; (OS p-value 0.008, DFS p-value 0.05). The posterior margin was the most common positive single CRM-positive site (44 %), followed by anterior (39 %) and lateral sites (17 %). However, the anterior margins carried poorer OS and DFS compared to posterior and lateral sites, (p-values 0.37 and 0.39 respectively). Conclusion This study demonstrated that CRM involvement as defined by RCP was an independent prognostic factor for both survival and recurrence in esophageal cancer. It promoted the value of additional reporting CRM-0mm in CRM-R1 cases. The study also investigated the relative importance of reporting CRM-R1 location, which might be a useful prognostic tool in the future.