In the detection of pancreatic ductal adenocarcinoma, blood tests to detect mutations in ctDNA, specifically in the KRAS gene, have been combined with protein biomarkers that include carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9) and cancer antigen 125 (CA125) [40]. The gene discussed is CEACAM5; the disease is pancreatic ductal adenocarcinoma.