Intron 1 Polymorphism, Mutation and the Protein Expression of Epidermal Growth Factor Receptor in Relation to the Gefitinib Sensitivity of Korean Lung Cancer Patients

Background : Epidermal growth factor receptor (EGFR) intron 1 polymorphism in non-small cell lung cancer (NSCLC) has been found to have therapeutic implications for the patients treated with EGFR tyrosine kinase inhibitors. However, its clinical significance as related to gefitinib responsiveness is still controversial. We examined CA repeat polymorphism in intron 1 of the EGFR gene and its relation with the EGFR gene mutation in NSCLC patients who were treated with gefitinib. Methods : Sixty seven patients who were treated with gefitinib were analyzed for intron 1 polymorphism in the EGFR gene, the EGFR mutations and the EGFR protein expression. Two hundred twenty seven samples of NSCLC were analyzed for EGFR mutations. Results : CA repeat was low in 27 patients (40.3%) and high in 40 (59.7%) patients. The response rate for gefitinib therapy was higher in the patient population with a low number of CA repeats in the EGFR gene (p=0.047) and in the patients with the mutated type of EGFR (p= 0.048), though these two factors were not related. Thirty four patients (15.0%) harbored EGFR mutations. Conclusions : This study suggests that the intron 1 CA repeat polymorphism of the EGFR gene may serve as a predictor of the clinical outcome of NSCLC patients treated with gefitinib, and this without regard for EGFR mutation. Our data further supports the importance of EGFR mutations with regard to a distinct clinical profile and the prognostic implications for NSCLC patients.