CtDNA detection using liquid biopsy (droplet digital PCR (ddPCR) utilizing KRAS G12/13 and, if negative, Q61 commercial test kits) was prospectively performed on patients with stage IV pancreatic cancer i) prior to initiation of systemic chemotherapy and ii) serially every 2 weeks until restaging. The gene discussed is KRAS; the disease is pancreatic neoplasm.