Endobronchial ultrasound-guided transbronchial needle aspiration for identifying epidermal growth factor receptor mutations

Abstract

Objective To assess the usefulness of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) to detect epidermal growth factor receptor (EGFR) mutations in cells recovered fiom malignant mediastinal nodes from patients with non-small-cell lung carcinoma (NSCLC).Methods From February 2010 to July 2010,26 cases of mediastinal lymph node biopsy specimens were diagnosed as lung adenocarcinoma by EBUS.Needle puncture site for the EBUS was standard 22G needle,once cytology pathology diagnosed adenocarcinoma,at the same site with the conventional needle puncture method to obtain the biopsy specimen which would be save in the saline solution.After centrifugation,the specimen was extracted DNA throuugh TIANamp Micro DNA Kit,and to detect EGFR exon 19 and 21 in use of mutation enriched method improved by our department.First of all,through specific digestion of wildtype EGFR gene restriction enzyme cutting,and then amplificated by polymerase chain reaction (PCR).For most wild-type gene had been broken as the PCR reaction template can not be made,the mutant gene amplification product increased substantially.Results All 26 patients were successfully extracted DNA,16 were male and 10 female,mean age of 62.1 years (34 to 79 years).EBUS puncture mediastinal lymph nodes,cytology pathology have shown that large numbers of adenocarcinoma cells with lymphocytes visible in the background.Somatic mutations of the EGFR gene were detected in 12 of 26 cases (46.2％ ),7 cases of exon 19 mutation,5 cases of exon 21 mutation.All samples were verified by sequencing,14 negative cases were negative in DNA sequencing,7 of 12 cases were positive for DNA sequencing,the other 5 cases were negative.4 patients of 12 cases of patients with EGFR mutations had a radical surgery after neoadjuvant chemotherapy,tumor specimens were tested again with EGFR gene mutation,the same result as the preoperative test results.Conclusion EBUS-TBNA mediastinal lymph node biopsy in the detection of EGFR mutations in tissue samples was feasible,through the highly sensitive methods,higher detection rate was availabie,the result can be used as evidence of EGFR inhibitor therapy. Key words: Non-small cell lung cancer; Endobronchial ultrasound-guided transbronchial needle aspiration; Epidermal growth factor receptor