Analysis of epithelial cells isolated from hyperplastic enlarged lobular units (HELUs). HELUs arise from the enlargement of normal terminal duct lobular units by hyperplastic columnar epithelial cells and are the earliest histologically identifiable precursor of breast cancer.
Lee S, Medina D, Tsimelzon A, Mohsin SK et al. Alterations of gene expression in the development of early hyperplastic precursors of breast cancer. Am J Pathol 2007 Jul;171(1):252-62. PMID: 17591970