Chromosome and gene alterations in breast cancer as markers for diagnosis and prognosis as well as pathogenetic targets for therapy.

Chromosomal abnormalities have been implicated in cancer development since the turn of the last century. Only during the past two decades, with advances in cytogenetics and molecular biology, has the genetic basis of neoplasia been firmly established, however, with chromosomal alterations being recognized as critical in the pathogenesis of human cancer. Recurrent chromosomal alterations provide cytological and molecular markers for the diagnosis and prognosis of disease. They also facilitate the identification of genes that are important in carcinogenesis and, ultimately, may lead to the development of targeted therapy. In breast cancer, the most prevalent malignancy among females, substantial progress has been achieved in identifying genes located at sites of recurrent chromosomal alterations and in profiling gene expression through the application of powerful cytogenetic and functional genomic techniques. Characterization of the molecular pathologic characteristics and gene-expression profiles of breast cancer should provide new clinical tools for the accurate diagnosis and prediction of prognosis as well as new targets for the development of therapeutic agents.