The use of CA-50 radioimmunoassay inhibition test in the differential diagnosis of benign and malignant liver diseases.

The value of a radioimmunoassay (RIA) in the detection of the human carcinoma-associated antigen CA-50 has been assessed in 50 normal subjects, 28 patients with various benign liver diseases and 91 patients with primary and secondary liver carcinomas. Sera from all normal subjects and 25 of 28 (89 per cent) patients with benign liver diseases had a CA-50 level below 17 units/ml. Three patients with sclerosing cholangitis and sixty (66 per cent) patients with primary or secondary liver tumours had CA-50 levels above 17 units/ml. CA-50 may therefore be a useful tumour marker for the diagnosis of liver carcinomas and for the post-treatment monitoring of patients with various liver malignancies.