CEACAM5 and cancer: Clinical application strategies could include labeling the liver metastasis with a tumor-specific monoclonal antibody such as anti-carcinoembryonic antigen (anti-CEA) conjugated to a fluorophore [5–10] or labeled by a telomerase-dependent cancer-specific adenovirus that contains the GFP gene, OBP-401 [11, 12, 17–19].