CYP2D6 and non-small cell lung carcinoma: Pharmacogenetic analyses revealed that gefitinib metabolism by CYP2D6 to form O-desmethyl gefitinib was affected by the CYP2D6 genotype consisting of *5 and *10 with a clear gene dosage effect, which is consistent with the previous results obtained for Japanese patients with advanced NSCLC [27].