The 'Real R0': A Resection Margin Smaller Than 0.1 cm is Associated with a Poor Prognosis After Oncologic Esophagectomy

Background Although resection margin (R) status is a widely used prognostic factor after esophagectomy, the definition of positive margins (R1) is not universal. The Royal College of Pathologists considers R1 resection to be a distance less than 0.1 cm, whereas the College of American Pathologists considers it to be a distance of 0.0 cm. This study assessed the predictive value of R status after oncologic esophagectomy, comparing survival and recurrence among patients with R0 resection (> 0.1-cm clearance), R0+ resection (≤ 0.1-cm clearance), and R1 resection (0.0-cm clearance). Methods The study enrolled all eligible patients undergoing curative oncologic esophagectomy between 2012 and 2018. Clinicopathologic features, survival, and recurrence were compared for R0, R0+, and R1 patients. Categorical variables were compared with the chi-square or Fisher’s test, and continuous variables were compared with the analysis of variance (ANOVA) test, whereas the Kaplan-Meier method and Cox regression were used for survival analysis. Results Among the 160 patients included in this study, 113 resections (70.6%) were R0, 34 (21.3%) were R0+, and 13 (8.1%) were R1. The R0 patients had a better overall survival (OS) and disease-free survival (DFS) than the R0+ and R1 patients. The R0+ resection offered a lower long-term recurrence risk than the R1 resection, and the R status was independently associated with DFS, but not OS, in the multivariate analysis. Both the R0+ and R1 patients had significantly more adverse histologic features (lymphovascular and perineural invasion) than the R0 patients and experienced more distant and locoregional recurrence. Conclusions Although R status is an independent predictor of DFS after oncologic esophagectomy, the < 0.1-cm definition for R1 resection seems more appropriate than the 0.0-cm definition as an indicator of poor tumor biology, long-term recurrence, and survival.