Purpose: This study aimed to assess (1) the prognostic value of circulating tumor DNA (ctDNA) and (2) the ability of ctDNA to detect recurrence compared with standard surveillance in curatively resected early-stage biliary tract cancer (BTC).
Methods: This retrospective, multicenter cohort study evaluated serial ctDNA testing for surveillance in patients with early-stage BTC after curative resection. We evaluated the relapse-free survival (RFS) by ctDNA positivity. The sensitivity of ctDNA in detecting a confirmed recurrence of BTC, defined as a biopsy-proven or true progression by radiographic tumor dynamics, was evaluated. The lead time was calculated from the first ctDNA detection to the confirmed recurrence.
Results: A total of 56 patients with curatively resected stage I-III BTC were included in this study, with a median follow-up of 12.8 months from the date of surgery. ctDNA detection during the molecular residual disease window period (median RFS, 6.6 months v not reached; hazard ratio [HR], 26 [95% CI, 2.6 to 265]; P < .0001) and during the surveillance period (median RFS, 19.3 months v not reached; HR, 20 [95% CI, 2.6 to 153]; P < .0001) were associated with poorer RFS. Sixteen patients had confirmed recurrence. ctDNA identified recurrence in 93.8.% (15/16) of the recurred patients with an average lead time of 3.7 months. Carbohydrate antigen 19-9 levels did not show any significant correlation with RFS (HR, 1.17 [95% Cl, 0.24 to 5.71]; P = .844) in contrast to ctDNA.
Conclusion: The findings from our real-world cohort study revealed the (1) promising value of ctDNA as a prognostic biomarker for relapse in curatively resected BTC and (2) potential early detectability of recurrence by ctDNA compared with standard surveillance.