[Clinical significance of serum sialyl Tn antigen in patients with gynecological cancer. STN Study Group].

Serum sialyl Tn antigen was assayed in gynecological cancer and benign patients by means of "STN OTSUKA" kits. Fifty-eight of 140 (41.1%) ovarian cancer patients showed a significant elevation of sialyl Tn antigen in serum above the cut-off level of 45 unit/ml (mean +2SD) determined from normal controls. There was no feature of positive frequency in tissue type, including serious carcinoma (47.6%), mucinous carcinoma (45.5%), clear cell carcinoma (30.4%) and endometrioid carcinoma (55.6%), but the positive frequency of mucinous carcinoma (36.8%) was higher than that of serous carcinoma (11.1%) in stage I. Compared with other markers, sialyl Tn antigen showed a very much lower false-positive rate (3.6%) in benign gynecological diseases. In the diagnosis of ovarian cancers, the combination assay of sialyl Tn antigen and CA 125 increased diagnostic efficiency compared with any other combination assays. Therefore, sialyl Tn antigen will be a useful tumor marker for ovarian cancers.