Using microarray analysis as a prognostic and predictive tool in oncology: focus on breast cancer and normal tissue toxicity.

Microarray analysis makes it possible to study the expression levels of tens of thousands of genes in one single experiment and is widely available for research purposes. Gene expression profiling is currently being used in many research projects aimed at identifying gene expression signatures in malignant tumors associated with prognosis and response to therapy. An important goal of such research is to develop gene expression-based diagnostic tests that can be used to guide therapy in cancer patients. Here we provide examples of studies using microarrays, especially focusing on breast cancer, in a wide range of fields including prediction of prognosis, distant metastasis and local recurrence, therapy response to radio- and chemotherapy, and normal tissue response.