Redefining Resection Margin Status and Its Implications for Adjuvant Radiotherapy in Hilar Cholangiocarcinoma: A 10-Year Retrospective Study of Recurrence Patterns

Abstract

Background. This study aimed to redefine resection margin classification by considering the clearance length and high-grade dysplasia of the margin, as well as to evaluate the association between adjuvant radiotherapy and recurrence patterns. Methods. The study retrospectively analyzed 218 patients who underwent curative-intent resection between 2012 and 2022. Resection margins were categorized as wide-clear (>2 mm), narrow-clear (<= 2 mm or clear margin after re-resection), dysplastic, or invasive. Recurrence patterns and the effect of adjuvant radiotherapy on local recurrence-free survival were assessed across these margin groups. Results. Overall recurrence occurred for 62.1% of the patients. The local recurrence rates per margin were as follows: wide-clear (23.6%), narrow-clear (32.6%), dysplastic (35.3%), and invasive (31.4%). The patients receiving adjuvant radiotherapy had a significantly lower local recurrence (adjusted hazard ratio [HR], 0.097; 95% confidence interval CI 0.033-0.286; p < 0.001). Notably, no local recurrence was observed in patients from the wide-clear, narrow-clear, or dysplastic groups who received adjuvant radiotherapy. In the invasive-margin group, the patients who received adjuvant radiotherapy had a lower risk of local recurrence (adjusted HR 0.04; 95% CI 0.01-0.24; p < 0.01). Conclusions. The refined margin classification showed distinct recurrence patterns. Adjuvant radiotherapy was associated with local recurrence in patients with invasive margins and in those with dysplastic or narrow-clear margins, including cases with R0 status achieved through re-resection. More tailored postoperative strategies that incorporate the margin status might help to address recurrence risk of hilar cholangiocarcinoma.