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.