Role of CD44 in nonpalpable T1a and T1b breast cancer

Primary infiltrating ductal carcinomas (IDCs) of the breast which measure less than 0.5 cm (Tla lesions) and between 0.5 and 1.0 cm (T1b lesions) are associated with a small risk of nodal metastasis, The role of axillary dissection in Tla and T1b breast cancer is controversial. In the absence of axillary dissection, comparable prognostic information mip ht be obtained by examination of the primary cancer. The adhesion molecule CD44 represents a family of transmembrane proteins that mediate cell-cell and cell-matrix interactions. Previous investigators have correlated expression of CD44 and its isoforms with prognosis in breast cancer. We investigated the value of CD44 isoform expression as a predictor of nodal metastases in nonpalpable Tla and T1b IDC. Monoclonal antibody against the standard form of CD44 (CD44s) and polyclonal antibody directed against the variant isoform (CD44v6) was tested on 34 cases of nonpalpable node-negative infiltrating ductal carcinoma (IDC) less than 1.0 cm and 9 cases of nonpalpable node-positive IDC less than 1.0 cm. The expression of CD44s was significantly decreased in node-positive Tla and T1b IDC versus node-negative Tla and T1b IDC (11% vs 65%). In contrast, 97% of the node-negative LDC and 100% of the node-positive IDC expressed the CD44v6 isoform, We conclude that CD44s expression is significantly altered in Tla and T1b IDC with nodal metastases but that the CD44v6 isoform does not correlate with nodal metastases in nonpalpable stage Tla and T1b IDC. HUM PATHOL 28:772-778. Copyright (C) 1997 by W.B. Saunders Company.