Inter-patient heterogeneity in radiation-induced DNA damage responses is proposed to reflect intrinsic variations in tumour and normal tissue radiation sensitivity, but the prediction of phenotype by a molecular biomarker is influenced by clinical confounders and assay reproducibility. | Intra-patient and inter-patient comparisons of DNA damage response biomarkers in Nasopharynx Cancer NPC Analysis of NCC0901 randomised controlled trial of induction chemotherapy in locally advanced NPC