CEA is expressed by more than 90% of colorectal cancers, as well as by a large number of other carcinomas, including esophageal, stomach, lung, breast, pancreas, uterus, and ovarian cancer. It has been shown that this tumor marker can serve as a useful target for radiolabeled antibodies. Since CEA-Scan uses a small antibody fragment at a low dose, there is virtually no immune reaction by subjects to the foreign protein. In addition, linking the fragment with technetium-99m, a common radioisotope in nuclear medicine, permits tumor detection within a few hours, using conventional gamma cameras.
CEA-Scan comprises an antibody fragment (Fab') against the tumor marker, carcinoembryonic antigen ("CEA").
Each year there are approximately 134,000 new cases of colorectal cancer in the United States; colorectal cancer is estimated to kill over 55,000 Americans annually. Trials are also under way for lung and breast cancer indications.