Conventionally, cancer-related protein markers have been used to monitor patients with limited sets of cancers for recurrent disease, i.e. CA-125 in ovarian cancer, AFP for hepatocellular carcinoma, carcinoembryonic antigen (CEA) for colorectal adenocarcinoma, or lactate dehydrogenase (LDH) for malignant melanoma. Here, CEACAM5 is linked to cancer.