Recent advances in transcription profiling of human cancer.

During the past 20 years, significant success in the therapy of certain cancer types has given rise to the hope that cancer will soon be curable. However, survival rates of most patients diagnosed with cancer have not substantially increased. Instead, it is becoming clear that many tumor types, which were previously regarded as homogeneous disease entities, are composed of different subtypes which lead to varying patient prognosis and survival rates. These findings complicate diagnosis and treatment of cancer patients and call for new anti-oncogenic therapies. DNA microarrays are powerful tools to investigate global gene expression in tumors and their corresponding normal tissues, to classify tumors based on their molecular properties, and to identify novel targets for future tumor therapy. Recent results of global gene expression analyses in various tumor types are reviewed, and their implications for diagnosis and therapy of human cancer are discussed.