Fundamental and clinical evaluation of IRMA for serum pancreatic oncofetal antigen (POA)

The value of immunoradiometric assay (IRMA) for serum pancreatic oncofetal antigen (POA) was fundamentally and clinically evaluated using a commercially available POA IRMA kit (SD-8708). Laboratory test for POA IRMA kit yielded satisfactory results for incubation, reproducibility, dilution, recovery, and specificity. The use of the present IRMA system enabled the measurement to be completed within four hr. Serum levels of POA obtained from 70 healthy volunteers ranged from 3.5 to 18.0 U/ml, with the cut-off level defined as 13.6 U/ml. Using this figure, the serum POA level was false-positive in 37 % of 84 patients with benign diseases. In 181 patients with malignant diseases, the serum POA level was frequently much higher than the cut-off level for pancreatic cancer, cholangiocarcinoma, hepatoma, gastric cancer, and lung cancer. There was no significant correlation between serum POA and CEA levels in 157 patients with malignancy; nor was correlation significant between serum POA and CA 19 - 9 levels, except for the colorectal cancer group. Concurrent measurement of both serum POA and CA 19 - 9 levels increased positive rate for malignant disease, especially cholangiocarcinoma (100 %) and pancreatic cancer (95 %). The present IRMA system for POA would become a routinely available diagnonstic aid for the tumor marker, and would be even more helpful if combined with serum CA 19 - 9 level. (Namekawa, K.)