Gene expression-driven diagnostics and pharmacogenomics in cancer.

The advancement of microarray technologies for characterizing tumors at the gene expression level has made a significant impact on the field of oncology. Profiling gene expression of various human tumors has led to the identification of gene expression patterns or signatures related to tumor classification, disease outcome and response to therapy. This technology can also be used to study the mechanism of action of specific therapeutics. Routine application of microarrays in clinical practice will require significant efforts to standardize the array manufacturing techniques, assay protocols and analytical methods used to interpret the data. Extensive, independent validation using large, statistically sound datasets will also be necessary. Studies on gene expression profiling of clinically relevant tissue samples with the aim of finding gene markers to support disease prognosis and therapy decisions are reviewed.