RESEARCH ARTICLE Reduced CYP2D6 function p

Full list of author information is available at the end of the articleBackground Compared to cytotoxic agents, gefitinib and erlotinib are orally available epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) that prolong survival, have few hematological adverse events, and improve the quality of life in non-small cell lung cancer (NSCLC) patients with EGFR-active gene mutations [1-6]. The major adverse events that occur with gefitinib and erloti-nib therapy are rash, liver dysfunction and diarrhea [1-5,7-10]. We are always faced with a decision to select between these drugs in clinical practice for patients with EGFR-active mutations. In general, erlotinib is associated with higher toxicity and lower tolerability than gefitinib because the dose of erlotinib used is nearly equal to the maximum tolerated dose, whereas the dose of gefitinib used is close to the minimum active dose [11,12]. Recent in vitro studies have reported different metaboli