P2.09-14 The Detection of EGFR Gene Mutation from Washing Solution of Devices used for the Bronchoscopic Examination

Abstract

The detection of epidermal growth factor receptor (EGFR) gene mutation is necessary for selection of lung cancer treatment. Recently, biopsy specimens are used in many genomic and immunohistochemical examination methods to select the treatment policy, so it is important not to waste valuable cancer cell samples. For detection of EGFR gene mutation we examine the washing solution of devices used for the bronchoscopic examination in order to solve the issue. In this report, we investigate the detection ratio of EGFR mutation using this cytological sample. A total of 336 washing solution samples from lung cancer patients were examined for EGFR gene mutation testing in the period between November 2010 and October 2017. 328 cases of 336 excepting 8, which were carried out as re-biopsy, were surveyed in this examination. After the regular biopsy or scraping method, all devices were washed with 10ml saline liquid. Half volume of washing solution was used for regular cell examination to detect cancer cells. Only if a sufficient amount of non-small cancer cells were observed from it, the other volume was submitted for EGFR mutation examination. Final diagnosis was decided by histological specimen. Presence or absence of EGFR mutation and their types were observed from 328 samples retrospectively. Histological diagnosis of all 328 biopsy specimens are as follows; 200 Adenocarcinoma (AD), 100 Squamous cell carcinoma (SQ), 13 non-small cell lung carcinoma(NSCLC), 3 adenosquamous cell carcinoma(ADSQ), 7 high grade neuroendocrine carcinoma (HGNEC), and 5 others. The detection number of EGFR mutation from AD, SQ, ADSQ and NSCLC are 65, 4, 2, and 3 respectively. There is no EGFR mutation from remaining histology cases. In all of 74 EGFR mutation positive cases, Exon 19 deletion was detected in 33 cases (45%) and Exon 21 L858R was detected in 33 cases (45%). The detection rate of EGFR gene mutation from washing solution of devices is 33% (65/200) in AD and 4% (4/100) in SQ. These results are approximate to previous reports. Consequently, it is acceptable to use this method to investigate EGFR gene mutation of non-small lung cancer patients. Furthermore, it is an advantage that we can carry out an EGFR mutation test using this method with a cytology sample earlier than a method with a histology sample.