P38 RESECTION MARGINS AFTER ONCOLOGICAL ESOPHAGECTOMY ; DOES THE DEFINITION OF THE R STATUS MATTER?

Abstract

Abstract Aim This study aimed to compare long-term survival and recurrence of patients depending on their R status: R0 (>1mm of clearance), R1 (positive margins with 0mm clearance) and R0+ (margins with <1mm clearance). Background & Methods Resection margin (R) status is a known prognostic factor after curative esophagectomy. Different definitions of microscopic margin involvement are currently used. The American College of Pathologists defines R1 as a direct contact of the tumor with the resection margin (0mm), whereas the Royal College of Pathologists considers a positive margin as being within 1mm distance (<1mm) from the tumor. All consecutive patients between 2012-2018 undergoing a curative esophagectomy for squamous cell cancer or adenocarcinoma of the esophagus or gastroesophageal junction were included. Clinical features, overall survival and recurrence were compared between patients with R0, R1 and R0+ status, with a specific subgroup analysis of locally advanced (cT3/4) tumors to eliminate baseline differences. Categorical variables were compared with the x2 or Fisher’s exact test, continuous variables with the ANOVA tests, whereas the Kaplan-Meier method with the log rank test was used for survival analyses. Results Among the 174 included patients, 126 (72.5%) resections were R0, 14 (8%) R1 and 34 (19.5%) R0+ resection. R0 patients had a better overall (OS) (median 59 months, 95%CI 34-84) and disease-free survival (DFS) (median not reached) compared to R1 (OS 20 months, 95%CI 8-32, DFS 9 months, 95%CI 7-11) and R0+ patients (OS 24months, 95% CI 19-29, DFS 13, 95%CI 3-23). Pairwise comparison revealed a similar OS (p=0.47) but a trend to better median DFS for R0+ patients compared to R1 (p=0.051). Within the locally advanced subgroup, R0 patients also had a better OS (median 59 months versus 20 months for R1 and 24 months for R0+, p=0.012) and DFS (33 months versus 9 and 18 months respectively, p<0.001). Conclusion R0 resection has a superior overall and disease-free survival after esophagectomy than R1 and R0+. A margin clearance of <1mm had a similar overall survival as a direct positive margin, whereas in more advanced tumor stages, the distinction between R1 and R0+ only seems relevant regarding tumor recurrence.