The expression of CEA, CA 19-9 and HMFG antigens in ovarian clear-cell and endometrioid carcinomas

The tumour antigen expression of ovarian and endometrial endometrioid carcinomas, ovarian clear-cell carcinomas as well as endometrial and cervical clear-cell carcinomas were immunohistochemically compared. Of special interest were potential differences between the endometrioid and clear-cell carcinomas of the ovary. The expression of CEA and CA 19-9 tumour antigens in all these tumour types was heterogeneous, with 10-20% of the cases being positive for CEA and 40-75% being positive for CA 19-9. In contrast, HMFG IIIC 12, a monoclonal antibody originally directed against human milk fat globule (HMFG) membrane antigens, invariably detected a corresponding antigen on every case of these tumour types. Another HMFG antibody, SM IF 3, on the other hand, detected antigenic material on all clear-cell tumour types, but only rarely on endometrioid tumours of the ovary or endometrium. While HMFG IIIC 12 detects an antigen present on all ovarian, endometrial and mammary carcinomas, antibody SM IF 3 thus appears to be more restricted in its staining patterns. Our results with both of these antibodies indicate that ovarian clear-cell carcinomas and ovarian endometrioid carcinomas have antigenic differences, which provides further evidence that they belong to different tumour entities.