Epidermal growth factor receptor mutation in Chinese patients with non-small cell lung cancer

Abstract

BACKGROUND & OBJECTIVE: Recent studies showed that somatic mutations in epidermal growth factor receptor (EGFR) tyrosine kinase (TK) domain are associated with sensitivity of non-small cell lung cancer(NSCLC) to TK inhibitor gefitinib. The mutations, including in-frame deletions at exon 19 and substitutions at exon 18 or exon 21, cluster around ATP-binding pocket of TK domain. The frequency of mutations are higher in Japanese patients than in American patients. This study was to analyze EGFR mutations in Chinese patients with NSCLC. METHODS: From Jun. to Oct. 2004, fresh specimens of lung cancer and corresponding normal lung tissue were collected from 52 consecutive NSCLC patients (39 men and 13 women) treated in Cancer Center of Sun Yat-sen University. All patients had not received treatment of gefitinib. DNA was extracted from the 52 specimens. Exons 19 and 21 were amplified by polymerase chain reaction (PCR), and sequenced and analyzed from both sense and antisense directions. RESULTS: Somatic mutations in TK domain of EGFR in tumors were identified from 10 of the 52 (19.2%) patients, including 7 cases of in-frame deletion in exon 19 and 3 cases of amino acid substitution in exon 21. Mutation rate was significantly higher in adenocarcinoma, adeno-squamous carcinoma, and bronchioloalveolar cancer than in squamous cell carcinoma [26.1% (6/23), 40.0% (2/5), and 50.0% (2/4) vs. 0 (0/20), P=0.025], and significantly higher in non-smokers than in smokers [41.8% (7/17) vs. 8.6% (3/35), P=0.009]. Mutation rate in women was similar to that in men [23.1% (3/13) vs. 18.0% (7/39), P=0.697]. CONCLUSION: EGFR mutation rate in Chinese NSCLC patients is similar to that in Japanese patients, and is obviously higher than that in Caucasian population.