Clinical Significance of an R1 Resection for Pancreatic Ductal Adenocarcinomas Treated by Intensive FOLFIRINOX Induction-Based Chemotherapy and Extended Pancreatectomies.

[BACKGROUND] This study assessed the prognostic significance of an R1 resection after intensive FOLFIRINOX (FX) neoadjuvant chemotherapy in patients with borderline (BL) and locally advanced pancreatic ductal adenocarcinomas.

[METHODS] We retrospectively analyzed data collected from January 2010 through December 2024 at a single center.

[RESULTS] A total of 219 consecutive patients (31 borderline and 188 locally advanced) underwent resection for pancreatic ductal adenocarcinoma after induction FX chemotherapy; the median number of preoperative cycles was 11 (range: 2-26). Venous resection was present in 191 patients (87.7%) and arterial resection in 141 patients (64.4%). R1 resection was observed in 73 patients (33.4%). The median overall survival (OS) from surgery was 30 months (95% confidence interval [CI] 21.3-38.6), with 1-, 3-, and 5-year survival rates of 77%, 45%, and 32%, respectively. R1 resection (hazard ratio [HR] 1.47; 95% CI 1.01-2.14; p = 0.004) was identified as an independent prognostic factor for OS, along with normalization of carbohydrate antigen 19-9 before surgery (HR 0.68; 95% CI 0.47-0.99; p = 0.04) and positive lymph nodes (HR 1.95; 95% CI 1.23-3.09; p = 0.004). R1 resection was associated with shorter OS (20 vs. 40 months; p < 0.0001) and disease-free survival (5 vs. 9 months, p = 0.005) than R0 resection. Patients with an R1 resection exhibited a lower histological and biological response to preoperative chemotherapy (p < 0.05).

[CONCLUSIONS] An R1 resection after intensive induction chemotherapy by FX, undertaken in about one-third of resection cases, is a major prognostic factor associated with reduced long-term survival.