[Transcriptome analysis in cancerology: bioinformatics aspects]

Recent technological advances (e.g. various DNA arrays and chips) allow the measurement of expression level (mRNA abundance) for thousand of genes simultaneously, over multiple conditions or time. Initially developed and tested on model systems such as yeast or in vitro cell line cultures, these techniques have recently begun to be applied to the analysis of human cancers. Initial results are promising, and large-scale gene expression profiling is now expected to become a clinical tool for better tumour identification, prognosis, and optimal treatment design. It is thus important that clinicians become familiar with the theoretical principles underlying the interpretation of gene expression profiles as used in three different contexts: gene discovery, tumour class prediction, and molecular diagnosis. This is the purpose of the present article.