A biomarker is a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. The discovery and development of proper biomarkers is a critical part of modern oncology. Among the many different types of biomarkers, cell receptors have demonstrated important roles as diagnostic, prognostic, and predictive biomarkers in cancer research and therapy, leading to their integration into drug development trials. In breast cancer, Estrogen/Progesterone receptors and HER2/neu receptors are two good examples of biomarkers that are prognostic of outcomes, as well as predictive of response to certain therapies. Limitations exist, however, such as the invasive procedures required obtaining tissue, and the difficulty measuring the actual distribution of the receptors. Thus, continued efforts to develop receptors as comprehensive cancer biomarkers with novel approaches is mandated to further advance the modern oncology.
Keywords: Biomarker; Cancer prognosis; Cancer thserapy; Circulating free DNA; Clinical response; EGFR mutations; Estrogen receptor; HER2/neu; Hormonal therapy; Hormone receptor status; Novel therapeutics; Nuclear receptors; Predictive marker; Progesteron receptor; Receptor; Type 1 biomarkers; Type 2 biomarkers.