Survival benefit with adjuvant radiotherapy after resection of distal cholangiocarcinoma: A propensity‐matched National Cancer Database analysis

Abstract

No convincing evidence for the benefit of adjuvant radiotherapy (RT) following resection of distal cholangiocarcinoma (dCCA) exists, especially for lower-risk (margin- or node-negative) disease. Hence, the association of adjuvant RT on survival after surgical resection of dCCA was compared with no adjuvant RT (noRT). Using National Cancer Database data from 2004 to 2016, patients undergoing pancreatoduodenectomy for nonmetastatic dCCA were identified. Patients with neoadjuvant RT and chemotherapy and survival <6 months were excluded. Propensity score matching was used to account for treatment-selection bias. A multivariable Cox proportional hazards model was then used to analyze the association of adjuvant RT with survival. Of 2162 (34%) adjuvant RT and 4155 (66%) noRT patients, 1509 adjuvant RT and 1509 noRT patients remained in the cohort after matching. The rates of node-negative disease (N0), node-positive disease (N+), and unknown node status (Nx) were 39%, 51%, and 10%, respectively. After matching, adjuvant RT was associated with improved survival (median, 29.3 vs 26.8 months; P < .001), which remained after multivariable adjustment (HR, 0.86; 95% CI, 0.80-0.93; P < .001). Multivariable interaction analyses showed this benefit was seen irrespective of nodal status (N0: HR, 0.77; 95% CI, 0.66-0.89; P < .001; N+: HR, 0.79; 95% CI, 0.71-0.89; P < .001) and margin status (R0: HR, 0.58; 95% CI, 0.50-0.67; P < .001; R1: HR, 0.87; 95% CI, 0.78-0.96; P = .007). Stratified analyses by nodal and margin status demonstrated consistent results. Adjuvant RT after dCCA resection was associated with a survival benefit in patients, even in patients with margin- or node-negative resections. Adjuvant RT should be considered routinely irrespective of margin and nodal status after resection for dCCA. Adjuvant radiotherapy after resection of distal cholangiocarcinoma was associated with a survival benefit in patients, even in patients with margin-negative or node-negative resections. Adjuvant radiotherapy should be considered routinely irrespective of margin and nodal status after resection of distal cholangiocarcinoma.