Response to second-line erlotinib in an EGFR mutation-negative patient with non-small-cell lung cancer: make no assumptions

Erlotinib-an oral tyrosine kinase inhibitor (TKI) of the epidermal growth factor receptor (EGFR) has commonly been used as a therapeutic option in metastatic non-small-cell lung cancer (NSCLC) patients in the second- or third-line treatment setting. A mutation in the EGFR gene (EGFR M+) confers an increased response to this class of drugs. In the first-line setting, use of Tic's is restricted to patients having a mutation. The importance of this biomarker has been questioned in subsequent treatment lines. Here, we report a case showing a positive response to erlotinib treatment in the second-line setting. The patient, an elderly male smoker with stage IV NSCLC, had a tumour that was EGFR mutation-negative (wild-type EGFR). Based on this clinical case, we discuss the controversy concerning the need for, and impact of, testing for EGFR mutation after first-line treatment.