Serum and tissue measurements of CA72-4 in ovarian cancer patients

Serum levels of cancer-associated antigen 72-4 (CA72-4) (tumor-associated glycoprotein 72; TAG-72) from 106 patients with primary ovarian cancer were measured by an immunoradiometric assay employing the monoclonal antibodies (MAbs) B72.3 and CC49. Immunohistochemical localization of TAG-72 was also investigated using immunoperoxidase methodology in conjunction with both light and electron microscopy. In using a cutoff value of 4.0 U/ml for the serum assay, sensitivity of all primary ovarian carcinomas was 63.2% (67.6% of mucinous cystadenocarcinomas and 66.7% of serous cystadenocarcinomas), while specificity of benign ovarian tumors was 91.1%. Diagnostic characteristics of CA125 and CA72-4 have been demonstrated by receiver-operating-characteristics analysis. Although CA125 expressed a remarkable diagnostic efficiency with serous cystadenocarcinoma, it was less efficient with mucinous cystadenocarcinoma. CA72-4, however, was highly detectable for any histological type of ovarian cancer. Immunohistochemical staining with MAbs B72.3 and CC49 in the cytoplasm was stronger than that in the cell membrane in tissues from mucinous cystadenocarcinomas. Also, histological localization of TAG-72 in the microvilli and apical cytoplasmic membrane was demonstrated by electron microscopy using MAb B72.3 and samples of seromucinous cystadenocarcinoma (mixed type). Consequently, TAG-72 was useful for the detection of ovarian carcinoma, especially for monitoring mucinous cystadenocarcinoma, and it is localized in the microvilli and apical cytoplasmic membrane of cystadenocarcinoma cells.