The EGFR gene mutation frequency discrepancies are best explained on the basis of the selection criteria employed in this study restricting the eligible NSCLC patients to those receiving an erlotinib treatment, in spite of including all of the NSCLC patients, together with some patient’s non-availability of tumour tissue which precluded an accurate EGFR gene mutation estimate. This evidence concerns the gene EGFR and non-small cell lung carcinoma.