As the prognosis of pancreatic cancer, a kind of malignant tumor, remains poor due to the low diagnostic rate at the early stage, there is still a significant clinical need to determine individualized tumor molecular profiles and personalized risk for recurrence. Circulating tumor cells (CTCs) and exosomes from patients with primary tumors may hold promise in serving as an informative biomarker to address this clinical need. Here in this study, the investigators are going to explore the feasibility and safety of sampling portal venous blood via endoscopic ultrasound (EUS), and detect portal venous CTCs and analyze mRNA markers of exosomes by RNA-seq. The investigators aim to explore the potential molecular mechanisms in tumor microenvironment and mechanisms of drug resistance.
