Vertical R1 margins are not always associated with residual neoplasia after endoscopic resection of Barrett's neoplasia: a nationwide cohort with dedicated pathology reassessment

BACKGROUND: To evaluate the proportion of patients with residual neoplasia after endoscopic resection (ER) for Barrett's neoplasia with confirmed tumor-positive vertical resection margin (R1v). METHODS: Retrospective cohort study including all patients treated with ER for Barrett's neoplasia with histologically documented R1v since 2008 in the Dutch Barrett Expert Centers. R1v was defined as cancer cells touching the vertical resection margin and Rx as not assessable margins. Reassessment of R1v specimen was performed by experienced pathologists until consensus was reached regarding vertical margins. RESULTS: 101/110 included patients had macroscopically complete resections (T1a n=17, T1b n=84), of which 99/101 (98%) ER specimens were reassessed. Reassessment confirmed R1v in 74 (75%) patients and found Rx in 16% and R0 in 9%. Presence of residual neoplasia could be assessed in 66/74 patients during endoscopic reassessment (n=52) and/or in the surgical resection specimen (n=14), of whom 33/66 (50%)had residual neoplasia. Residual neoplasia detected during endoscopy was always endoscopically visible and biopsies from a normal appearing ER-scar did not detect additional neoplasia. Twenty-five patients with no residual neoplasia during endoscopic reassessment underwent endoscopic follow-up for median 37 months(IQR 12-50), in which 4 developed a local recurrence(16.0%), all detected as visible abnormalities. CONCLUSIONS: Histological evaluation of ER margins appears challenging as 75% of documented R1v cases were confirmed during reassessment. After ER with R1v, 50% of the patients had no residual neoplasia. Endoscopic reassessment 8-12 weeks after ER seems accurately able to detect residual neoplasia and help to determine the most appropriate strategy for patients with R1v.