Even in the much larger trials looking at either Cetuximab or the TKI Gefitinib or Erlotinib in NSCLC, the lack of assay standardisation has left us with a somewhat confusing picture regarding the relative importance of mutations (which seek key for single agent activity of the TKI in NSCLC) versus overexpression of EGFR which may be sufficient for radiosensitisation. This evidence concerns the gene EGFR and non-small cell lung carcinoma.