Background: Researchers have worked for decades to solve the enigma of cancer. We know that essential checkpoints in the life cycle of cells have to be disrupted in order to create a tumour cell, and some of the genes and proteins involved have been identified. Most of the previous work on identifying these genes have been based on "educated guesswork", as the methods and technologies used have been limited to the examination of genes one by one, or a few at a time.
Material and methods: Microarray technology allows tens of thousands of genes to be examined at the same time, without any previous information on the genes. Both expression levels and copy numbers of the genes can be evaluated. Our studies of breast cancer and bone tumours are presented, as well as examples from the literature.
Results and discussion: Microarray analyses have been used to produce molecular portraits of breast cancer, malignant melanomas and other cancers. These portraits may help in sub-classification of tumours, in prognosis, and in the general understanding of cancer. For example, studies of gene expression patterns of breast carcinomas, similar with respect to classic prognostic markers (such as ER status, grading and morphology), have identified subgroups of patients that show differences in survival.