The microarray technique allows the classification and prognostic assessment of cancers based on gene expression. Specific gene expression profiles can be created for individual cancer types or risk groups. With this information, it is possible to improve the classification and prognosis estimation of tumor diseases. Another area of application is the prediction of the efficacy of anti-cancer drugs. This is important for the individual therapy of tumor diseases. INTER-ARRAY® produces appropriate DNA arrays for the diagnostic repertoire in cancer detection and treatment.