Epigenetic markers and response to chemotherapy in cancer.

The last ten years has seen an explosion in interest in epigenetic mechanisms of control of gene expression. This is particularly true in the field of cancer research where epigenetic alterations are now regarded as equally important as genetic alterations in the development and progression of cancer. Of particular interest is altered DNA methylation, which is a key feature of essentially all tumour types. Aberrant methylation of CpG islands represents an ideal candidate for both diagnostic and prognostic markers in cancer. It is highly prevalent, very largely tumour specific and potentially far more readily detectible than most genetic alterations. This review will discuss the genes already identified as potential epigenetic markers of drug response, as well as the rapidly improving technology for detection of methylation which has greatly expanded the potential sources of tumour specific DNA that can be used for epigenetic marker analysis.