Patel H, Okamura R, Fanta P, et al. - In order to determine the clinical utility of circulating tumor DNA (ctDNA) (the liquid biopsy) in advanced pancreatic ductal adenocarcinoma (PDAC), researchers undertook this investigation. They examined ctDNA in 112 patients with PDAC (54–73 genes). They also analyzed tissue DNA in 66 patients (315 genes) (both clinical-grade next-generation sequencing). TP53 and KRAS were identified as the most common genes altered in ctDNA. The median number of characterized ctDNA changes per patient was 1 (range, 0–6), but significantly higher numbers of ctDNA alterations were observed in patients with advanced PDAC vs those with surgically resectable disease. In this study, ≥ 1 ctDNA alteration was detected in 75% (70/94) of advanced tumors. For TP53 and for KRAS, the concordance rate between ctDNA and tissue DNA alterations was estimated to be 61% and 52%, respectively. According to the findings, ctDNA frequently harbored unique changes some of which may be targetable. A poor prognostic factor for survival was higher ctDNA levels.