Prognostic value of the circumferential resection margin and its definitions in esophageal cancer patients after neoadjuvant chemoradiotherapy

The accepted importance of a positive circumferential resection margin (CRM) (defined as R1 in the TNM classification) is based on histopathology of the resection specimen obtained after primary surgery in esophageal cancer patients. The aim of this study is to look for the prognostic value of CRM after neoadjuvant chemoradiotherapy and to compare the clinical significance of a histologically CRM < 1 mm from the cut margin (Royal College of Pathologists definition of R1) to a positive cut margin (College of American Pathologists definition of R1) and to >= 1 mm margin (R0) resections in patients with ypT3-esophageal tumors after neoadjuvant chemoradiotherapy. Between 2000 and 2014, 458 patients who received esophagectomy after neoadjuvant chemoradiation therapy were selected. Overall (OS) and disease-free survival (DFS) were calculated by means of Kaplan-Meier curves and compared by Cox regression analysis. There were 163 (35.9%) patients who had a ypT3 tumor; in 118 (72.4%) resection was complete (R0). In 37 (22.7%) patients a CRM < 1 mm was found and 8 (4.9%) had a circumferential R1-resection. CRM involvement was inversely correlated with tumor regression grading, lymph node capsular involvement, and number of positive lymph nodes. On univariate analysis, no statistically significant difference was found between R0-resection and CRM < 1 mm (P = 0.103) for OS, but DFS showed a significant difference (P = 0.025). Circumferential R1-resections showed a significant difference compared to R0-resections for OS and DFS (both P = 0.002). In multivariate analysis, extracapsular lymph node involvement and circumferential R1-resection were withheld as independent prognosticators for OS, whereas extracapsular lymph node involvement, absence of regression on the primary tumor and circumferential R1-resection were withheld for DFS. After correcting for different variables in the multivariate model, CRM < 1 mm showed no statistical difference compared to R0-resections neither for OS nor for DFS. After neoadjuvant chemoradiotherapy, CRM is correlated with biological behavior of the tumor and with therapy response. Furthermore it is an independent prognosticator for OS and DFS. However CRM < 1mm itself is no independent prognosticator for OS nor DFS survival in multivariable analysis. These results suggest that the definition of R1-resection should be limited to true invasion of the section plane.