Biomarkers in lung cancer: Present status and future perspective -what is a useful biomarker for lung cancer?

Biomarkers have been defined as having a characteristic that is objectively measurable and evaluable as an indicator of normal biologic processes, pathogenic process, or pharmacologic response to a therapeutic intervention. In most instances, they are proteins or their fragments, DNA and RNA, low molecular compounds. In lung cancer, molecular markers are expected to play roles in early detection and screening, in anticipation of a therapeutic response and outcome (prognosis), and the safety of the treatment. Future clinical trials are closely associated with the prognosis and response to the treatment.