Prognostic Significance of Extrapancreatic Invasion in Pancreatic Cancer: Excellent Outcomes in Patients With Disease Confined Within the Pancreas

BACKGROUND/AIM: Extrapancreatic invasion (EPI) is a well-known adverse prognostic factor in pancreatic cancer; however, whether the absence of EPI defines a distinct clinical entity remains unclear. This study aimed to clarify the clinicopathological features and prognosis of pancreatic ductal adenocarcinoma (PDAC) confined within the pancreas. PATIENTS AND METHODS: A total of 199 patients who underwent curative-intent pancreatectomy for PDAC between 2012 and 2022 were retrospectively analyzed. Patients were classified into EPI-negative (n=19) and EPI-positive (n=180) groups. Clinicopathological characteristics, recurrence-free survival (RFS), and overall survival (OS) were compared between the two groups. RESULTS: EPI-positive tumors were significantly associated with higher CA19-9 levels, larger tumor size, lymph node metastasis, and lymphovascular/perineural invasion. None of the EPI-negative patients experienced recurrence within 3 years or disease-specific death within 5 years. Multivariate analysis identified the absence of EPI as an independent favorable prognostic factor for both RFS and OS. CONCLUSION: PDAC confined within the pancreas, without EPI, represents a biologically distinct subset with remarkably favorable outcomes. Assessing EPI status may aid in tailoring perioperative treatment strategies and preventing overtreatment in selected patients.