[Enzyme immunoassay (EIA) as an assay system of tumor markers]

To detect a small amount of tumor marker in the serum, the development of a sensitive assay system has been tried. In the beginning radioimmunoassay was mainly employed. But the use of radioisotope has been undesirable because the special facilities to treat radioactive substance or to discard it are required. For this reason the various assay systems without the radioisotope have been developed. Among them EIA system is in the mainstream, especially for the determination of CEA and AFP. Recent analysis shows the increasing trend of the employment of EIA for the determination of other tumor markers. In EIA system it is critical to keep the regulation of reaction time to be obtain the accurate value. Autoassay system is favorable for this problem. It is also another problem that discrepancies of assayed value are seem among the different assay kits. In the clinical use of tumor marker the comparison of the serial data, even if they are obtained from the different hospitals, is important. So overcoming this problem is desirable.