HPB SO24 - Recurrence Pattern of Pancreatic Ductal Adenocarcinoma based on Time-to-Recurrence: A 5-year Single-Centre Retrospective Study

Abstract Background A vast majority of patients with pancreatic ductal adenocarcinoma (PDAC) develop early disease recurrence, even after curative-intent surgical resection. Understanding the pattern of disease recurrence will enable identification of areas for improvement within the preoperative diagnostic and management algorithms for these patients. The aim of the retrospective cohort study was to compare the recurrence pattern of PDAC in patients with early (<12 vs >12 months) and very early (<6 vs >6 months) recurrence following surgical resection. Method A retrospective review of histologically confirmed pancreatic ductal adenocarcinoma patients who underwent pancreaticoduodenectomy (N=151) between 2015-2020 at a tertiary HPB centre was undertaken. All patients underwent CT and PET-CT for initial staging before resection. Initial recurrence after resection was identified through postoperative imaging and/or HPB MDT outcomes. Early recurrence (ER) was defined as recurrence within the first 12 months after surgery (n=78). Additionally, very early recurrence (VEM) was defined as recurrence within the first six months after surgery (n=46). Statistical analysis was performed using GraphPad Prism 8.0. Results In total, 117 (77.5%) of patients experienced recurrence, with a median recurrence-free survival of 11.3 (5.1-19.6) months. Patients with ER had significantly higher pathological T staging (p=0.01), greater margin positivity rate (p=0.01) and higher lymph node ratio (p=0.046), while those in VER had significantly larger maximum tumour diameter and number of involved lymph nodes (p=0.04) compared to their counterparts. Patients with ER (47.4 vs 31.5%, p=0.046) and VER (60.9 vs 30.5%, p<0.001) had significantly greater rates of liver metastasis compared to their counterparts. There were no differences in loco-regional recurrence, peritoneal or pulmonary metastasis between the groups. Conclusion Approximately 20% of patients undergoing surgical resection for PDAC developed liver metastasis within six months of surgery. This raises concerns for the presence of micro-metastatic disease within the liver unidentified on preoperative imaging. Therefore, there is a need to enhance preoperative imaging and treatment algorithms to improve survival of patients with PDAC.