Tissue distribution of TAG-72 in malignant mixed mullerian tumors of the uterus

Malignant mixed mullerian tumors are the most frequent sarcomas arising from the uterus. Since these tumors are traditionally associated with a poor prognosis, tumor-associated antigens may be useful in the evaluation and follow-up of affected patients. The purpose of this study was to determine the frequency and tissue distribution of TAG-72, an antigen frequently expressed in endometrial carcinomas, and to compare it to CA 125 and CA 19-9 expression in malignant mixed mullerian tumors of the uterus. Consecutive, paraffin-embedded sections from 35 tumors were immunohistochemically evaluated using primary antibodies directed against the tumor-associated antigens. These antigens were demonstrated in the neoplastic glandular epithelium and not in the sarcomatous portion of the tumor. The degree of antigen expression was unrelated to the nature of the sarcomatous element present (homologous vs heterologous). Positive staining (≥5% of the glandular epithelium) for TAG-72 was present in 66% of the tumors; another 6% of the tumors contained focal staining (<5% of the glandular epithelium) for TAG-72. Although cytoplasmic and intraluminal staining were present, cell surface staining was the most prominent feature of TAG-72 expression. Tumors were more likely to be positive for TAG-72 than either CA 125 (P = 0.046) or CA 19-9 (P = 0.004). The extent of TAG-72 expression was unrelated to the extent of disease (intrauterine vs extrauterine) and overall patient survival. However, antigen expression was correlated with the differentiation of the glandular component present. Although the biological significance of TAG-72 expression by neoplastic epithelium is unknown, this antigen may offer advantages in the assessment of affected patients.