Detection of circulating tumor antigens.

A wide variety of malignancies have associated tumor antigens. Two which have proven useful in the clinical detection and management of cancer are alphafetoprotein (AFP) and the carcinoembryonic antigen (CEA). These materials have been determined both by radioimmunoassay and by a newer technique employing enzymes to replace radioisotopea as markers. The interpretation of these immune assay results and the factors governing the shape of the standard curve are discussed. The advantages of 57Co over 22Na as a volume marker in radioimmunoassay are presented.