OGC P19 The future insights of evaluating the circumferential resection margin (CRM) status in oesophageal cancer: A 12-year cohort study

Abstract Background The definition of CRM (circumferential resection margins) for oesophageal cancers varies among the international pathological bodies with an ongoing controversy about the optimal definition. There is also no enough data about the prognostic relevance of different sites in CRM. In this study, we examined the prognostic impacts of different CRM distances and sites. Methods This study included patients who had curative oesophagectomy for oesophageal cancer between 2010 till June 2021. Follow up till April 2022 was achieved. CRM status was carefully examined for the distance and site of involved tumour cells. Patients with involved proximal or distal margins were excluded. The outcomes between different CRM margins were retrospectively analysed. The long-term follow up data was obtained via direct contact with the patients during our oncological clinics, cross-checked with our hospital/national patients’ electronic databases. Results 456 patients were included in this study. Involved tumour cells within 1mm of CRM was observed in 192 patients (42.1%). CRM+ (<1mm) was associated with worse overall (OS) and disease-free survival (DFS) (22.8 and 16.3 months respectively) compared to CRM-negative (47.7 and 45.1 months respectively), (p-value <0.001 for both). CRM+ (0mm) had worse OS and DFS (20.5 and 12 months respectively) compared to CRM+(0.1–1mm) (26.4 and 20 months respectively), (p-values 0.028 and 0.006 respectively). CRM-positive posterior margin was the most common involved site (32%), but was associated with better OS and DFS compared to anterior and lateral sites, (p-values 0.1 and 0.08 respectively). Conclusions The site and distance of tumour cells within CRM should be rigorously assessed in oesophagectomy specimens. The presence of tumour cells within 1mm of CRM was an independent factor for OS and DFS. The CRM+(0 mm) had significant lower survival rates compared to other CRM+ distances (0.1–1 mm). The involved margin sites within CRM had different survival rates, with superiority towards posterior resection margins.