Abstract 4669: EGFR gene mutation analysis in Chinese lung cancer patients: value for differentiation diagnostics and therapeutics

Abstract

Abstract There have been a lot studies focusing on EGFR mutation analysis in the patients of lung cancer especially in the patients with adenocarcinoma, for EGFR mutation has shown helpful in patient prognosis and therapeutic selection. Erlotinib and Gefitinib are playing increasing role in late stage adenocarcinoma of lung although it has not been listed as a first line treatment for advanced patients of Asian ethnic yet. However, the fact of a better respond rate to Erlotinib and Gefitinib and longer survival related to the mutant status of EGFR gene among Asian patients is encouraging the use for routine test of this gene in clinical service for lung cancer patients. Ninety two Chinese cancer patients were included into the study, from which 60 were lung cancer. The other cases were 11 supraclavicular lymph node biopsies and 21 tumor masses of different sites with differentiation diagnosis needed. EGFR mutation analysis was performed in DNA extracted from tumor tissue or biopsy samples. Overall mutation rate of EGFR was 42.39% (39/92) in whole patient group. The mutation rate in lung cancer was 46.67% (28/60) whereas it turned to 58.14% (25/43) when only looking at adenocarcinoma (56.10%, 23/41) and adenosquamous carcinoma (100%, 2/2). No mutation was found in squamous carcinoma, large cell carcinoma and poorly differentiated carcinoma. EGFR mutation analysis in the samples from Endobronchila Ultrasound-Guided Transbronchial Needle Aspiration (EBUS-TBNA) for mediastinal masses revealed an EGFR mutation rate of 42.86% (3/7), mimicking the mutation rate of lung cancer in our study. Forty eight percent of the EGFR mutation was located in exon 19 and 36% of the mutation in exon 21. Mutation of exon 19 seemed to be lower in the patient group older (35.71%, 5/14) than 58 year old (median age) than that in the patient group younger than 58 year old (58.82%, 10/17) (P=0.0581). In opposition, mutation rate of exon 21 appeared higher in the older group (64.29%, 9/14) than that in the younger patient group (23.53%, 4/17) (P=0.0800). The mutations in male patients were mainly located in exon 19 (71.43%, 10/14). And the mutation rate of exon 19 and 21 in female patients showed very close (43.47%, 10/23 for exon 19 and 47.83%, 11/23 for exon 21). Mutation rate of exon 20 was generally low but showed a higher rate in younger and female patients (17.65% and 13.04%). Mutation of supraclavicular lymph node was quite high (36.37%, 4/11) while mutation rate from variant site was low (20.00%, 4/20). One adenocarcinoma located in uterus muscle layer was demonstrated to possess an exon 19 mutation. All follow up analysis is in process. In conclusion, EGFR mutation analysis is a useful tool in defining patients suitable for EGFR TKI treatment as well as helpful in differentiation diagnosis in metastasis lesion. Mutation analysis in the samples derived from EBUS-TBNA is especially of important with clinical value. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4669.