KRAS and cancer: Cell‐free circulating tumor DNA (ctDNA), also known as liquid biopsy, is a noninvasive biomarker in various cancer.6 It was reported that specific gene mutations in ctDNA can be used as diagnostic and prognostic markers in pancreatic cancer.7 Kras is the most frequently reported oncogenic mutation in ctDNA of pancreatic cancer with the rate ranging from 65% to 85%.8 Several studies identified that Kras mutation in ctDNA plays a prognostic role in pancreatic cancer.9 However, Kras‐related target therapy or immune treatment almost failed to improve survival in clinical trials.10, 11