cDNA microarrays: identification of gene signatures and their application in clinical practice.

Sequencing of human genome introduced the new postgenomic era in medicine. A novel microarray technology represents a novel genetic platform which is being widely exploited to bridge the gap between gene sequence and function. Basically, with this technique it is possible to simultaneously measure the activity of virtually all genes in the genome. The result of these experiments are spots whose brightness varies from gene to gene corresponding to the transcriptional activity of the examined genes. It makes it possible to create experiments looking for genes whose expression correlates with the presence of tumor, with progression from a benign to a malignant condition, or with progression from a low grade to high grade malignancy. Tumor types can be more specifically identified, and differences in gene expression can be used to detect tumors that already demonstrate gene expression changes associated with increased risk of metastasis. Gene expression profiles will also help clinicians make decisions about the optimal treatment of cancer patients.