Can R Status after Resection Be Predicted "A Priori" in Pancreatic Ductal Adenocarcinoma? A Proposal of Novel Simplified Radiological Criteria

Introduction: Negative surgical margins (R0) impact local recurrence and survival in pancreatic cancer (PDAC). Anticipating R status prior to surgery is warranted. Patients and Methods: Patients undergoing pancreatic resection with curative intent for PDAC were identified. Using the CT scans at time of diagnosis, the 2019 NCCN borderline resectability criteria were compared to novel criteria: Presence of any alteration of the superior mesenteric-portal vein (SMPV) and perivascular stranding of the superior mesenteric artery (SMA). Accuracy of predicting R status was evaluated. Results: 593 patients undergoing resection for PDAC (2010-2018) were identified. 325 (54.8%) patients underwent upfront surgery while 268 (46.2%) received neoadjuvant therapy. In upfront resected patients, positive SMA stranding was associated with 67% R1 rates while positive SMA stranding and SMPV alterations together showed R1 rates of 78%. In contrast to these criteria, the 2019 NCCN borderline criteria failed to predict margin status. In patients undergoing neoadjuvant therapy, only perivascular SMA stranding remained a predictor of R status, leading to a rate of 33% R1 resections. SMA stranding was related to higher clinical T stage (p=0.003) and clinical N stage (p=0.043) as well as perineural invasion (p=0.022). SMA stranding was associated with worse survival in both patients undergoing upfront surgery (36 vs. 22 months, p=0.002) and neoadjuvant therapy (47 vs. 34 months, p=0.050). Conclusion: The novel criteria were accurate predictors of R status in PDAC patients undergoing upfront resection. After neoadjuvant treatment, likelihood of positive resection margins is approximately halved, and only perivascular SMA stranding remained a predictive factor.