Galactosyltransferase Associated with
Tumor (
GAT) was clinically studied in cases of
ovarian cancer. When two cut-off levels of
GAT were compared, the cut-off level of 16 U/ml (which corresponds to mean + 2SD among healthy females) was found to be more suitable than the cut-off level of 14 U/ml (the level maximizing the diagnostic efficiency between malignant and benign ovarian
tumors). When the
GAT positive rate was examined for gynecologic
tumors, the rate was 5.7% for benign
ovarian cyst, 6.6% for
endometriosis, 20.5% for
cervical cancer, 19.5% for
endometrial cancer, and 52.9% for
ovarian cancer. The
GAT positive rate for different histologic types of ovarian
carcinoma was relatively high for each type, e.g., 55.0% for
clear cell adenocarcinoma and 66.7% for
endometrioid adenocarcinoma. The
GAT positive rate increased gradually with the stage of
ovarian cancer. In patients with benign diseases, in particular
endometriosis, the
GAT positive rate was lower than the positive rate with any other simultaneously determined marker (
CA602, CA125, CA54/61, CA72-4, STN, and SLX). The
GAT level most weakly correlated with the level of any of the other markers assessed. An assay combining
GAT with
CA602 or CA54/61 resulted in a higher positive rate and a higher diagnostic efficiency, when compared with the assay for
GAT alone. The lower positive rate of
GAT in
endometriosis, when compared with the positive rate of other markers, suggests the usefulness of
GAT in distinguishing malignant ovarian
tumors from benign ovarian
tumors. The use of
GAT in a combination assay is expected to overcome the disadvantages of
CA602 or CA125.