BACKGROUND : The benefit of adjuvant therapy (AT) after curative resection of distal cholangiocarcinoma (DCC) remains unclear. The objective of the current study was to investigate the impact of AT on long-term survival of patients who underwent curative-intent resection for DCC.

METHODS : Patients who underwent curative-intent resection for DCC between 2000 and 2020 were identified from a multi-institutional database. The primary outcomes included overall (OS) and recurrence-free survival (RFS).

RESULTS : Among 245 patients, 150 (61.2%) patients received AT (chemotherapy alone: n = 43; chemo- and radiotherapy: n = 107) after surgical resection, whereas 95 (38.8%) patients underwent surgery only. Patients who received AT were younger, and more likely to have an advanced tumor with the presence of perineural invasion (PNI), lymph node metastasis (LNM), lymph-vascular invasion, and higher T categories (all p < 0.05). Overall, there was no difference in OS (median, surgery + AT 25.5 vs. surgery alone 24.5 months, p = 0.27) or RFS (median, surgery + AT 15.8 vs. surgery alone 18.9 months, p = 0.24) among patients who did versus did not receive AT. In contrast, AT was associated with improved long-term survival among patients with PNI (median OS, surgery + AT 25.9 vs. surgery alone 17.8 months, p = 0.03; median RFS, surgery + AT 15.9 vs. surgery alone 11.9 months, p = 0.04) and LNM (median, surgery + AT 20.0 vs. surgery alone 17.8 months, p = 0.03), but not among patients with no PNI or LNM (all p > 0.1).

CONCLUSIONS : AT was commonly utilized among patients with DCC. Patients with more advanced disease, including the presence of PNI or LNM, benefited the most from AT with improved long-term outcomes among this subset of patients.