Pathological Nodal and Vascular Involvement Significantly Impacts the Recurrence Risk in Different Time Frames in Patients With Resectable and Borderline Resectable Pancreatic Cancer

Objective: To investigate the long-term dynamics of recurrence risk and the significance of prognostic variables using conditional recurrence-free survival (C-RFS) analysis in neoadjuvant treatment (NAT) for resectable (R) and borderline resectable (BR) pancreatic cancer (PC). Background: C-RFS analysis assesses the probability of achieving additional RFS according to the RFS already accrued. Methods: Patients with NAT and subsequent resection for R/BRPC were enrolled. In the C-RFS analysis, the actual 5-year RFS (5yRFS) rate was calculated separately in the subgroup that had already gained a given amount of RFS. The significance levels of prognostic variables associated with 5yRFS were assessed regarding their time-dependent dynamics in a conditional fashion. Results: Among the total 397 patients, 160 survived for more than 5 years without recurrence after surgery (actual 5yRFS rate: 45%). The probability of 5yRFS incrementally increased based on the RFS already accrued. Pathological nodal and vascular involvement were significant influencers of 5yRFS. The patients with nodal involvement consistently remained at significantly higher risk of recurrence than those without, even after 5yRFS, whereas positivity of vascular involvement was significantly associated with the risk of recurrence only during the early postoperative period and lost its significance after 3yRFS accrued. Conclusions: In NAT for R/BRPC, the probability of gaining additional RFS increases as a function of RFS already accrued, and the significance of prognostic variables time-dependently evolves in their own patterns during the long-term postoperative period.