Tumor-associated glycoprotein distribution detected by monoclonal antibody B72.3 in salivary neoplasia.

The expression of tumor-associated glycoprotein (TAG-72), an oncofetal mucin-like tumor-associated glycoprotein derived from membrane-enriched fractions of metastatic breast carcinoma, has been detected by monoclonal antibody (MoAb) B72.3 in adenocarcinomas of breast, colon, lung, endometrium, pancreas, and ovary. The authors reported the scope of TAG-72 expression detected by MoAb B72.3 in salivary neoplasia. They examined 96 salivary lesions (53 malignant and 37 benign primary tumors, 2 metastatic carcinomas, and 4 other benign lesions) and 17 normal tissues from parotid glands and found: diffuse TAG-72 expression in 29 of 55 (53%) malignant tumors and 6 of 36 (17%) benign tumors and in no normal tissue; focal TAG-72 expression in 10 of 55 (17%) malignant salivary tumors, 10 of 37 (25%) benign salivary tumors (all benign mixed tumors), and 1 of 17 (6%) histologically normal parotid gland ducts. Any expression of TAG-72, whether diffuse or focal, was found to have a 71% sensitivity for detecting salivary malignant tumors, but an unacceptably low specificity for malignant lesions (57%). Alternatively, if only diffuse TAG-72 expression was regarded as indicative of malignancy, the specificity of diffuse TAG-72 expression was 86%, but sensitivity of detection decreased to 53%. The authors studied a subset of benign and malignant mixed tumors (BMT and MMT) and found that 12 of 15 (80%) MMT diffusely and strongly expressed TAG-72, 2 of 15 MMT (13%) expressed TAG-72 focally, and 1 MMT (7%) was nonreactive. By contrast, most BMT did not express TAG-72; only sparse, focal TAG-72 expression was seen in 10 of 27 (37%) BMT. If diffuse TAG-72 expression is considered indicative of malignancy, its sensitivity and specificity for malignant mixed tumors is 80% and 100%, respectively. The authors suggest that diffuse TAG-72 expression may resolve conflicts in determining whether or not a mixed tumor is malignant.