chapter  5
Comparative Genomic Hybridization and Copy Number Abnormalities in Breast Cancer
ByNicholas Wang, Joe Gray
Pages 15

The progression of normal breast epithelial cells from a normal state toward one

characterized by uncontrolled growth and metastatic behavior is caused by the

deregulation of key cellular processes and signaling pathways. These alterations

in normal cellular behavior are rooted in the accumulation of genomic and

epigenomic lesions that impact hallmarks of cancer, such as the ability of the cell

to control proliferation, undergo apoptosis, increase motility leading to invasion,

and alter angiogenesis. A suite of technologies has now been developed to assess

genomic and epigenomic aberrations that contribute to cancer progression. The

application of these has shown that genome copy number abnormalities (CNAs)

are among the most frequent genomic aberrations. Remarkably, these studies

have revealed that 10% to 15% of the genes in a typical carcinoma tumor may be

deregulated by recurrent genome CNAs and regions. Some of these genes

influence disease progress and so may be assessed to facilitate prognosis. Others

influence response to therapy and so may be assessed as predictive markers.

Some of these enable oncogenic processes, on which tumors depend for survival,

and so are candidate therapeutic targets. In most cases, array comparative

genomic hybridization (CGH) is the method of choice for their discovery and

may be used in some setting for clinical assessments of these abnormalities.

Accordingly, we review here several of the current array CGH technologies

available and the considerations needed when determining the technology most

applicable to a given study.