Tissue CA 125 and CA 19-9 in malignant, mixed mesodermal tumors of the uterus

Mixed mesodermal tumors of the uterus are biphasic neoplasms composed of both a malignant epithelium and a sarcomatous stromal component. Elevated levels of tumor-associated antigens, such as CA 125, have been reported in some patients with these tumors. The purpose of this study was to determine the frequency and tissue distribution of CA 125 and CA 19-9 in malignant mixed mesodermal tumors of the uterus treated with primary surgery. Consecutive, paraffin-embedded sections from 35 tumors were immunohistochemically evaluated using primary antibodies directed against CA 125 and CA 19-9. CA 125 and CA 19-9 were demonstrated in the neoplastic glandular epithelium and not in the sarcomatous portion of the tumor. The localization of CA 125 and CA 19-9 suggested that both antigens were epithelial secretory products. Positive staining (≥5% of the glandular epithelium) for CA 125 was present in 46% of the tumors; another 14% of the tumors contained focal staining (<5% of the glandular epithelium) for CA 125. Positive staining for CA 19-9 was demonstrated in 34% of tumors; another 17% contained focal staining for CA 19-9. The markers were concordant in 77% of the tumors examined. Antigen expression was unrelated to the nature of the sarcomatous element (homologous vs heterologous), the extent of disease, and patient survival. However, the epithelial component of these sarcomas frequently expressed these antigens and the degree of expression was related to the cell type and the histologic grade of the glandular element.