Breast carcinoma-associated antigen. An immunocytochemical study.

An antiserum raised against a high molecular weight fraction of a medullary carcinoma of the breast was used to study breast carcinomas by means of an indirect unlabeled antibody peroxidase-antiperoxidase (PAP) technic. Strong cytoplasmic staining was demonstrated in all of 30 breast cancers tested and in one of three intraductal papillomas. Weak cytoplasmic staining was detected in four of nine fibroadenomas, two malignant melanomas, and one of six carcinomas of the colon. No cytoplasmic staining was seen in 24 other specimens of breast tissue, including 12 specimens from patients who had fibrocystic disease and five fibroadenomas, or in 17 extramammary malignant tumors. The antiserum appears to identify a breast carcinopma-associated antigen.