Contemporary approaches to diagnostics and therapy in oncology are nowadays tightly coupled to novel findings of biomedical science. One of the main trends in molecular medicine is the development of methodologies enabling parallel monitoring of expression of large quantities of genes or proteins - so called functional genomics and proteomics. These techniques allow determination of differential gene expression, i.e. evaluation of differences in gene expression between two or more cell or tissue samples of different types (e.g. normal or cancer cells) or coming from different culture conditions. These approaches help in elucidating causes of malignant transformation and can serve as a base for development of targeted anticancer gene therapy, monitoring of patient response to treatment and prediction of further disease development. Genomic approaches have undergone rapid development in the last few years - from differential and subtractive hybridisation through differential display all the way to serial analysis of gene expression and DNA microarrays. Besides that, tissue and protein arrays and other proteomic approaches have been also used. Currently DNA microarrays covering expression of the whole human genome, having significant potential in oncological research and clinical praxis, have been used more and more frequently. Many new tumor growth and progression markers were found using such approaches. Some of these markers have been already successfully used in clinical practice (e.g. in breast cancer) for therapy optimisation and minimisation of patient discomfort.

        Key words: DNA chip, microarray, gene expression, DNA, RNA, hybridization, antitumor therapy, prognostic marker.