Karyotypic abnormalities in precursor lesions of human cancer of the breast.

Aneuploidy and structurally aberrant chromsomes were identified in most cultures of ductal epithelial cells from proliferative lesions of human fibrocystic disease. These were qualitatively similar to those observed in cells comprising overt invasive mammary cancers. This represents some evidence in support of views indicating that proliferative fibrocystic disease may represent a precursor lesion of cancer of the breast, if not indeed its earliest morphologic expression.