Cell-free DNA as a prognostic and predictive biomarker in resectable distal common bile duct cancer

Background: Cell-free DNA (cfDNA) as an oncological biomarker has drawn much attention in recent years, but very limited effort has been made to investigate the prognostic values of cfDNA in distal common bile duct (CBD) cancer.Methods: Plasma cfDNA was measured in 67 patients with resectable distal CBD cancer. Survival outcomes and the correlation of cfDNA with other conventional prognostic factors were determined.Results: cfDNA levels were significantly higher in female patients, and those with poor tumor differentiation, abnormal serum carcinoembryonic antigen (CEA) level, and stage III cancer. The significant prognostic factors included a high cfDNA level (>8955 copies/mL), abnormal serum CEA level, stage III cancer, and positive resection margins. Compared with patients with high cfDNA level, those with lower cfDNA level (=8955 copies/mL) had significantly better overall survival outcomes (74.4% vs 100% and 19.2% vs 52.6%, for 1- and 5-year survival rates, respectively, p = 0.001). The cfDNA level, perineural invasion, CEA level, and radicality were identified as independent prognostic factors for distal CBD cancer after multivariate analysis.Conclusion: Circulating cfDNA levels play a significant role in predicting the prognosis and survival outcome for resectable distal CBD cancer. Furthermore, acting as a promising liquid biopsy, cfDNA could serve as a prognostic and predictive biomarker in combination with current conventional markers to improve diagnostic and prognostic efficacy.