EUS Guided HVA and PVA for Circulating Tumor DNA in Patients

The discovery of cell-free circulating tumor DNA (crDNA) in blood and the maturation of technologies for ctDNA analysis have presented an attractive opportunity for minimally invasive "liquid biopsy" genomic diagnostics. The investigators plan to perform EUS-guided portal vein and hepatic vein aspiration in GI cancers patients. The aim of the current study is thus to examine the concentration of ctDNA in portal vein (EUS-guided PVA), hepatic vein (EUS-guided HVA) and peripheral blood to understand the first pass effect of the liver with gastrointestinal (GI) cancers, and the possibility of using ctDNA as a marker for preoperative staging, restaging after neoadjuvant chemotherapy, and monitoring for recurrence.