A method for distinguishing benign from malignant breast lesions utilizing antibody present in normal human sera.

A sensitive immunoperoxidase technique was utilized 1) to detect the presence in normal human serum of antibody directed against breast carcinoma cells (tumor associated antibody--TAA) and 2) to determine whether this antibody could be used to discriminate between benign and malignant breast epithelium in sections of formalin fixed paraffin embedded tissue. A total of 16 benign and 13 malignant breast lesions were examined for evidence of binding of human immunoglobulin, before and after application of normal human AB serum containing the putative tumor associated antibody--TAA. Malignant cells showed significant binding of human immunoglobulin (TAA); benign or normal cells did not. Clear immunohistological separation of benign and malignant breast lesions appears possible by this method.