Analysis of Mutations in Epidermal Growth Factor Receptor Gene in Korean Patients with Non-small Cell Lung Cancer: Summary of a Nationwide Survey

Lung cancer is the leading cause of cancer-related death in Korea, accounting for approximately 20% of all cancer deaths [1]. Non-small cell lung cancer (NSCLC) accounts for more than 85% of all lung cancers, and the majority of patients with NSCLC present at an advanced cancer stage (stage III or IV) [2]. In the last decade, several studies have been performed on the molecular stratification of NSCLC in order to provide targeted treatment based on activating or driver mutations in these tumors. Activating mutations in the epidermal growth factor receptor gene (EGFR) can be used as therapeutic targets for treatment of NSCLC. In the Iressa Pan-Asia Study, tumors with EGFR mutations showed a 71.2% clinical response to first-line treatment with gefitinib, while tumors with wild-type EGFR showed only a 1.1% response [3]. Since then, several randomized control studies have shown an association between activating EGFR mutation and response to EGFR tyrosine kinase inhibitors (TKIs) [4-9]. Patient selection is important for using EGFR TKIs as the first-line treatment. At present, analysis of EGFR mutations is the accepted method for identifying patient response to EGFR TKIs. Direct DNA sequencing is a standard method for identifying mutations and is commonly used in the Asia-Pacific region [10]. Any routinely available pathological specimen can be used for analyzing EGFR mutations, including formalin-fixed, paraffin-embedded tissues from surgical resections; small tissue biopsies; or cell block preparations. Several publications have reported the prevalence of EGFR mutations in patients with NSCLC [10-14]. The rates of EGFR mutations are higher in Asian countries than in Western countries. Further, rates of EGFR mutations in Korean patients range from 17.4% to 51.3% [10,15-22]. Therefore, we performed a nationwide study of EGFR mutations in Korean patients with NSCLC in order to provide reliable information on the incidence and characteristics of EGFR mutations. This study was led by the Korean Cardiopulmonary Pathology Study Group.