Adjuvant chemoradiotherapy vs chemotherapy for resectable biliary tract cancer: a propensity score matching analysis based on the SEER database.

Background: Although the role of adjuvant chemotherapy (CT) for resectable biliary tract cancer (BTC) is gradually recognized, the benefit of adjuvant chemoradiotherapy (CRT) is still controversial. Our study is designed to compare the prognosis of CRT versus CT in BCT patients.

Methods: Clinicopathologic characteristics of patients with operable gallbladder cancer (GBCA), intrahepatic bile duct cancer (IHBDC), or extrahepatic bile duct cancer (EHBDC) were obtained from the Surveillance, Epidemiology and End Results (SEER) database (2004-2015). Univariate and multivariate analyses were performed to identify prognostic factors for overall survival (OS). Selection bias were reduced by propensity-score matching (PSM). Kaplan-Meier analysis was used to estimate the survival time.

Results: Within 922 patients, 53.9% received adjuvant CRT, and 46.1% received adjuvant CT. Multivariate analysis showed age, primary tumor site, T stage, N stage, tumor size, number of removed lymph nodes, and treatment were independent risk factors for OS. Similar improvement of CRT on survival was identified by PSM in the matched cohort compared with CT (28.0 months vs. 25.0 months, p = 0.033), particularly in GBCA cohort (25.0 months vs. 19.0 months, p = 0.003). Subgroup analysis indicated CRT improved outcomes of patients with age ≥ 60, female, lymph nodes positive, tumor size ≥ 5 cm, and none removed lymph node diseases.

Conclusion: Adjuvant CRT correlated with improved survival in patients with resected BTC compared with adjuvant CT, particularly in GBCAs. In addition, patients with age ≥ 60, female, lymph nodes positive, tumor size ≥ 5 cm, and none removed lymph node diseases may receive more benefits from adjuvant CRT.