Improved Survival in Surgically Resected Distal Cholangiocarcinoma Treated with Adjuvant Therapy: a Propensity Score Matched Analysis

Background: Data on the efficacy of adjuvant therapy (AT) in distal cholangiocarcinoma (dCCA) is limited. This study aimed to determine the role of AT in resected dCCA and identify subgroups that benefit from AT. Methods: We conducted a retrospective review of surgically resected dCCA in the NCDB from 2004 to 2013. Patients who received AT or observation (OB) were matched by propensity score. Log-rank test was used to compare OS. Results: Of 1782 patients with resected dCCA, 840 (47%) were in the OB group and 942 (53%) in the AT group. AT was younger (64.0 vs. 68.7 years, p < 0.001), had less comorbidities (Charlson Deyo score 0) (74.6 vs. 68.0%, p < 0.001), and more likely to have private insurance (p < 0.001). AT was more likely to present with T3/T4 stage (72 vs. 57%, p < 0.001), N1/N2 disease (58 vs. 37%, p < 0.001), and positive surgical margins (26 vs. 16%, p < 0.001). After 1:1 propensity score matching, 500 OB and 500 AT patients were compared. AT was associated with better OS (HR 0.79; 95% CI 0.67–0.93). Median OS was 31 and 25 months for the AT and OB (p = 0.006). The 1-, 3-, and 5-year survival rates were 87, 46, and 31% for AT; 79, 39, and 24% for OB. Subgroup analysis revealed an associated survival advantage for AT in T3/T4 tumors (HR = 0.72; 95% CI 0.59–0.89), node positive disease (HR 0.70; 95% CI 0.56–0.87), and positive margins (HR 0.58; 95% CI 0.42–0.81). Conclusion: AT is associated with improved OS in resected dCCA, especially in T3/T4 tumors, node positive disease, and positive margins.