ABSTRACT
There is a growing interest in life science research in the use of expressed transcripts that form the basis of biological markers (biomarkers) and in addressing some of the challenging statistical issues that arise when attempting to validate them. Biomarkers have extensively been used across diagnostic and therapeutic areas of many life science disciplines, including clinical, physiological, biochemical, developmental, morphological, and molecular applications.1 Biomarkers have been dened as “cellular, biochemical or molecular alterations that are measurable in biological media such as human tissues, cells, or uids.”2 The ofcial denition, developed by the “Biomarkers de- nitions working group” of the NIH is3 “A biomarker is a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.” More recently the denition has been broadened to include more biological characteristics that can be objectively measured and evaluated as a biological indicator.4 A biomarker can refer to any measurable molecular, biochemical, cellular, or morphological alternations in biological media such as human tissues, cells, or uids.5
