Adjuvant Chemoradiation in Patients with Lymph Node-Positive Biliary Tract Cancers: Secondary Analysis of a Single-Arm Clinical Trial (SWOG 0809)

Background: SWOG 0809 is the only prospective study of adjuvant chemotherapy followed by chemoradiation focusing on margin status in patients with extrahepatic cholangiocarcinoma (EHCC) and gallbladder cancer (GBCA); however, the effects of adjuvant therapy by nodal status have never been reported in this population. Methods: Patients with resected EHCC and GBCA, stage pT2-4, node-positive (N+) or margin-positive (R1) who completed four cycles of chemotherapy followed by radiotherapy were included. Cox regression was used to compare overall survival (OS), disease-free survival (DFS), local recurrence, and distant metastasis by nodal status. DFS rates were compared with historical data via a one-sample t-test. Results: Sixty-nine patients [EHCC, n = 46 (66%); GBCA, n = 23 (33%)] were evaluated, with a median age of 61.7 years and an R0 rate of 66.7% and R1 rate of 33.3%. EHCC versus GBCA was more likely to be N+ (73.9% vs. 47.8%, p = 0.03). Nodal status did not significantly impact OS (hazard ratio [HR] 1.98, 95% confidence interval [CI] 0.86–4.54, p = 0.11) or DFS (HR 1.63, 95% CI 0.77–3.44, p = 0.20). Two-year OS was 70.6% for node-negative (N0) disease and 60.9% for N+ disease, while 2-year DFS was 62.5% for N0 tumors and 49.8% for N+ tumors. N+ versus N0 tumors showed higher rates of distant failure (42.2% vs. 25.0%, p = 0.04). The 2-year DFS rate in N+ tumors was significantly higher than in historical controls (49.8% vs. 29.7%, p = 0.004). Conclusions: Adjuvant therapy is associated with favorable outcome independent of nodal status and may impact local control in N+ patients. These data could serve as a benchmark for future adjuvant trials, including molecular-targeted agents.