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

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.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.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).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.