Liquid biopsies in pancreatic cancer: targeting the portal vein

Pancreatic cancer is a highly lethal malignancy with poor overall survival due to silent progression until primary tumor growth or metastatic dissemination develops clinical symptoms. Even in the minority of patients with early diagnosis and candidacy for curative intent surgery, postoperative recurrence after surgical resection is very frequent. Due to these findings, efforts to identify minimally invasive ways to provide earlier diagnosis and enhanced prognostication are increasingly warranted. Liquid biopsies assessing for tumor derived materials shed into the blood are a promising tool to accomplish this goal; however, in pancreatic cancer, peripheral blood analyses remain dependent on the degree of tumor burden with a prohibitively low yield until the cancer is widely metastatic. To overcome this limitation, increasing literature has emerged evaluating the possibility of portal venous blood as a new, potentially higher yield liquid biopsy target in pancreatic cancer. This review will discuss the current literature and clinical application potential of mesenteric vasculature, or portal venous blood, as liquid biopsies in the diagnosis, prognosis and management of patients with pancreatic cancer.