[DNA methylation: potential for diagnosis, prognosis and therapy--prediction in oncology]

In the last decades, a great variety of novel therapeutic regimens have become available for cancer. These therapies often are very specific and thus effective only in subsets of cancer patients. This has led to an increased need for the clinician to specifically choose the therapeutic strategy the patient profits most from, but at the same time avoiding over-treatment. This situation has a profound impact on the methods in diagnostic tumor pathology, since it requires precise pre-therapeutic tumor characterization to support the clinical management of the individual case. A common and early event in cancer is aberrant DNA methylation within gene regulatory regions which affects a variety of genes with different functions. Altered DNA methylation has been shown to carry prognostic as well as predictive information. As a DNA-based marker that can be analyzed in routine formalin fixed tissue, DNA methylation offers a series of technical advantages which allow for introduction into a routine lab. Here we review well established DNA methylation markers and discuss their potential for clinical use.