Gene expression-based diagnosis of efficacy of chemotherapy for breast cancer.

Development of a clear index to select drugs, i.e., accurate prediction of drug sensitivity, is important not only to obtain the maximum therapeutic effects of drugs, but also realize personalized medicine (tailor-made medicine). With the recent advancement in genome science represented by microarrays, molecular-level elucidation of many diseases including cancers has been progressing. It has been clarified that molecular information, such as gene expression profiles of cancer cells and gene polymorphisms in individual patients, affects not only cancer development and progression, but also therapeutic and adverse effects. The establishment of a therapeutic method by clinical application of this information has been progressing, in which the therapeutic effects of drugs are accurately predicted, and the maximum effects are obtained corresponding to cancer properties and patients' characteristics.