Liquid Biopsy for ctDNA in Peritoneal Lavage and Blood in Pancreatic Cancer

Pancreatic cancer (PC) is a deadly disease and surgical resection of the tumor is the only hope of cure. Approximately 20-25% of the PC patients are candidates for intended curative resection, but despite microscopically radical resection the majority of patients will have recurrent disease within 2 years. This indicates that most patients will harbour non-detected (i.e. occult) cancer cells at the time of resection. Studies suggest that free tumor cells in the peritoneum and in the blood are part of this occult disease burden, and that patients with such findings should not be operated but treated as having metastatic disease. However, the exact incidence of these tumor cells in an unselected cohort of patients undergoing pancreatic resection is unknown, and the potential impact on postoperative survival is also uncertain. In recent years, molecular biomarkers are increasingly being regarded as both predictive and prognostic tools for cancer patients. This study will use the most optimal available methods to investigate the incidence of biomarkers for tumor cells in the peritoneum and blood in PC patients, and to relate these findings to the final outcome of the resected patients. This project has become highly relevant since new treatment methods (i.e. Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC)) may be used to eradicate free tumor cells. A recent systematic review and meta-analysis demonstrated that PC patients with positive peritoneal cytology (Cy+) had a significant poorer survival than patients with negative peritoneal cytology (Cy-) (HR 3.18), and the authors concluded that Cy+ patients should not undergo surgery. This conclusion was supported by a significant lower overall survival and a higher peritoneal recurrence rate after resection of Cy+ patients when compared to Cy- patients. Agreement that Cy+ in resectable PDAC is a negative predictor of prognosis came from another recent meta-analysis and systematic review. However, this study also in