Comparison of "direct" and "indirect" zirconyl-phosphate technics for carcinoembryonic antigen determination in plasma from patients having benign or malignant disease.

A simplified "direct" zirconly-phosphate gel radioimmunoassay for carcinoembryonic antigen (CEA) is compared with the "indirect" method using reagents provided in the Roche¿ CEA kit. Statistical analysis shows that (1) the methods are comparable in sensitivity and specificity; (2) the values obtained are, in most case, interchangeable; (3) the results by the two methods are comparable both among patients who have colorectal cancer and among those who have other diseases. For general use, the direct assay has proven to be an adequate alternative to the indirect assay.