Expression of epitopes of the tumour-associated glycoprotein 72 and clinicopathological correlations in mammary carcinomas.

We analysed the immunohistochemical expression pattern of the distinct carbohydrate epitopes of the TAG-72 molecule, defined by the monoclonal antibodies (MAbs) B72.3, CC-49 and CC-83, in 92 breast carcinomas of different histological type, and in other histological components identified in the mammary tissue samples studied. The results were correlated with the clinico-pathological characteristics of the tumours, and with their proliferative activity, assessed by thymidine labelling index (TLI). Expression of the TAG-72 epitopes was detected in all the tumour histotypes analysed, but patterns of immunoreactivity tended to vary in relation to type and level of differentiation. The comparative analysis of the reactivities of the three anti-TAG-72 MAbs revealed differences in their ability to recognise neoplastic lesions. MAb CC-49 reacted with the highest percentage of tumours (82%), and also tended to yield the highest percentages of immunoreactive cancer cells, while B72.3 and CC-83 reacted with lower percentages of tumours (respectively, 55 and 51%), and identified lower percentages of immunoreactive cells. High levels of expression of the three TAG-72 epitopes were detected in areas of in situ ductal carcinoma. Comparatively lower levels of immunohistochemical positivity were found in atypical epithelial hyperplasia, normal mammary epithelium and epithelium with cystic disease. TAG-72 epitope expression was correlated with prognostic parameters. The synchronous expression of the three epitopes significantly correlated with large tumour size (> 2 cm), and with high histological grade. No correlations could be demonstrated between TAG-72 phenotypes and nuclear grade, lymph node status and proliferative activity (high versus low).