Immunohistochemical evaluation of sialosyl-Tn antigens in various ovarian carcinomas

Sialosyl-Tn (S-Tn) antigen, a cancer-related antigen, was expressed in 56.3% (36 of 64 cases) of the common epithelial carcinoma tissues. This antigen was moderately to strongly expressed in 83.3% (15 of 18 cases) of the mucinous adenocarcinomas. In contrast, it was weakly expressed in 31.3% (5 of 16 cases) of the serous adenocarcinomas. Expression of this antigen in ovarian mucinous tumors of borderline malignancy was 80% (4 of 5 cases), and the staining was moderately intense. S-Tn reactivity was found in 11.5% (3 of 26 cases) of benign ovarian neoplasms. The S-Tn antigen was not found in either normal ovarian tissues or the normal vaginal squamous epithelia. We conclude that the S-Tn antigen may be useful in the histological classification of ovarian carcinomas and in the determination of the malignant potential of such lesions. Moreover, because increases in serum S-Tn antigen were often accompanied by its positive expression in tumor tissues, the S-Tn antigen appears to be a tumor marker in sera with a high specificity for ovarian carcinoma, particularly mucinous adenocarcinoma.