Usefulness and Prognostic Impact of Preoperative Dynamic CT in the Diagnosis of Extrapancreatic Extension in Resectable Pancreatic Adenocarcinoma

Background/Objectives: Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal gastrointestinal cancers, and reliable preoperative predictors of aggressive tumor biology are essential for optimizing treatment strategies, particularly in resectable PDAC (RPDAC). This retrospective study evaluated the diagnostic accuracy of dynamic computed tomography (CT) for detecting extrapancreatic extension, peripancreatic plexus (PL), serosal (S), and retroperitoneal (RP) invasion, and assessed its prognostic significance. Methods: Ninety-four patients who underwent curative-intent upfront surgery for resectable PDAC between 2007 and 2020 were included. Dynamic CT was reviewed using standardized window settings (WL 35/WW 350) to identify soft-tissue projections extending beyond the pancreatic contour. Results: Pathological S, RP, and PL invasion occurred in 29.8%, 56.3%, and 17.0% of patients, respectively. Dynamic CT demonstrated accuracies of 73.4%, 76.6%, and 87.2% for S, RP, and PL invasion, respectively. Notably, patients with PL-positive CT findings had significantly poorer disease-specific survival (DSS) than those with PL-negative, with 3- and 5-year DSS rates of 37% and 0% versus 61% and 53% (p < 0.001). Multivariate analysis confirmed preoperative PL invasion as the only independent predictor of poor prognosis. Conclusions: Dynamic CT provides reasonable diagnostic performance for assessing extrapancreatic invasion. In addition, CT-identified PL invasion reflects aggressive tumor behavior and may justify consideration of neoadjuvant therapy, even in anatomically resectable disease.