Impact of adjuvant chemotherapy on outcomes after curative-intent surgery for biliary tract cancer: A 10-year retrospective single-center study.

e16273 Background: Surgical resection remains the mainstay of treatment for biliary tract cancers (BTCs). Although adjuvant capecitabine has been shown to reduce recurrence, the best adjuvant chemotherapy remains unclear and numerous practice differences exist. Methods: This study is a retrospective review of patients with BTCs who received curative-intent resection at one institution (Montefiore Medical Center) between 01/2014 and 04/2023. The primary outcome was relapse risk. Kaplan-Meier curves and Cox regression were used to analyze relapse-free and overall survival rates. Results: 146 patients met entry criteria. Median age was 72.2 years (IQR 62.4-77.9 months) and median follow-up time was 20 months (IQR 1-111 months). 35.6% of patients had gallbladder cancer and 64.4% cholangiocarcinoma. 57 patients (39%) relapsed and 30 patients (20.5%) died. 105 patients (71.9%) received adjuvant chemotherapy (41% single agent, 42.9% a double-agent regimen, and 16.2% triple-agent therapy). Examining individual factors (univariate analysis) revealed several linked to higher relapse risk. Patients with advanced cancer stages (III-IV vs I-II) had 2.1 times higher risk. Higher T stages also showed increased risk: 5.6 times greater for T2 and 6.7 times greater for T3 compared to T1. Additionally, positive lymph nodes (N+), elevated post-surgical CA19-9, and presence of lymphovascular or perineural invasion were all significantly associated with 1.88-2.78 times higher relapse risk. Surprisingly, receipt of adjuvant chemotherapy was associated with a higher relapse risk (HR 2.42, 95% CI 1.18, 4.95, p-value 0.015). The association between receipt of adjuvant chemotherapy and relapse remained significant (HR 2.41, 95% CI 1.09-5.35, p = 0.03), after adjusting for age, sex, residual CA19-9, and receipt of adjuvant radiation therapy. Higher overall stage (III-IV vs I-II) was identified as a significant predictor of poorer overall survival (OS) with a hazard ratio of 21.70 (2.94-27.70, p = 0.009). Node-positive disease (HR = 2.25, 1.05-4.80, p = 0.036) and relapse (HR = 3.61, 1.58-8.28, p = 0.002) were also independently associated with worse OS. Conclusions: Adjuvant chemotherapy is commonly given after curative-intent surgery for BTCs at our center. Numerous factors are associated with an increased risk of relapse. Receipt of adjuvant chemotherapy was associated with a higher relapse risk even after adjustment for multiple covariates; the reason for this association remains unclear. More studies are needed to better understand the role and best form of adjuvant chemotherapy in the treatment of BTCs.