Clinical Implications of Pre- and Postoperative Circulating Tumor DNA in Patients with Resected Pancreatic Ductal Adenocarcinoma

The clinical implications of pre- and postoperative KRAS-mutated circulating tumor DNA (ctDNA) present in patients with pancreatic ductal adenocarcinoma (PDAC) have remained an unresolved issue. This study sought to investigate the clinical significance of pre- and postoperative ctDNA analyses and their impact on the prognosis of PDAC patients. Digital droplet polymerase chain reaction detected ctDNA in pre- and postoperative plasma samples prospectively obtained from patients with resectable and borderline-resectable PDAC. Its associations with recurrence-free survival (RFS) and overall survival (OS) were analyzed. The patients were sorted according to the presence of pre- and postoperative ctDNA, and its ability to stratify prognosis was evaluated. The study analyzed 97 patients. Both pre- and postoperative ctDNA were detected in 9 patients, and neither was detected in 55 patients. Whereas 15 patients harbored only preoperative ctDNA, 18 patients had only postoperative ctDNA. The multivariate analysis showed that the presence of preoperative ctDNA was associated with poorer OS (P = 0.008) and that postoperative ctDNA was not associated with either RFS or OS. Survival did not differ significantly between the patients with a positive shift in ctDNA status and those without detectable pre- or postoperative ctDNA. For the patients with PDAC, the presence of preoperative ctDNA was significantly associated poor OS, whereas postoperative ctDNA was not associated with poor survival. A positive change in ctDNA did not affect patients’ survival.