Spratt, Daniel E., Daniel R. Wahl, and Theodore S. Lawrence. “Genomic-adjusted radiation dose.” The Lancet Oncology 18, no. 3 (2017): e127.
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We read with interest Jacob Scott and colleagues’study, which used gene expression profiling derived from a preclinical radiation-sensitivity index of cell lines, combined with mathematical modelling of the linear quadratic formula, to derive the genomic-adjusted radiation dose (GARD). The authors showed that GARD is prognostic of outcome, and therefore is by definition a prognostic biomarker. Additionally, the authors proposed that GARD predicts the therapeutic effect of radiotherapy and can therefore be used to adjust radiation dose. A predictive biomarker provides information on the effect of a therapeutic intervention in a patient. Thus, by definition the authors have reported the creation of both a prognostic and predictive biomarker. Such a finding would be, if confirmed, of immense importance because, despite there being numerous prognostic biomarkers, very few predictive biomarkers exist in radiation oncology.