Tumor markers as target substances in the radioimmunologic detection of malignancies

Although none of the known tumor markers, including the relatively new ones characterized by monoclonal antibodies, are sufficiently sensitive or specific as to be useful in the primary diagnosis of incipient malignancies, many of them turned out, nevertheless, to be of great clinical importance: their main field of interest lies in the surveillance of the already diagnosed patient in the post-operative phase. More recently some of them, e.g. tumor proteins like CEA and AFP, hormones (HCG), some enzymes, and monoclonal antibody-characterized membrane components, are used also as target antigens for the radioimmuno-detection (RAID) of carcinomas and their metastases. Most of the tumor marker antigens were already successfully used as targets for tumor imaging with radiolabelled antibodies; however, many immunological and technical problems still remain to be resolved.