Abstract 3065: Is cytology a suitable source of NSCLC tumor material for EGFR mutation testing

Somatic mutations in the epidermal growth factor receptor (EGFR) affect non small cell lung cancer (NSCLC) sensitivity to the EGFR tyrosine kinase inhibitor gefitinib. In many countries, prospective testing of NSCLC patients for EGFR mutations is required to determine patient suitability for gefitinib. Mutation profiling is usually performed on DNA extracted from tumour biopsy samples, however the acquisition of biopsy material from NSCLC patients is often difficult and, in some cases is not available, as diagnosis is routinely made by other means. Diagnostic cytology samples, obtained by fine needle aspiration (FNA), may provide an additional source of tumour material for molecular analysis. The aims of this project were to assess the suitability of FNA for EGFR mutation testing and optimisation of DNA extraction and mutation detection methods suitable for analysis of FNA material. FNA smears of 3 human cell lines, obtained from mouse xenografts, were used to optimise DNA extraction methods. DNA was extracted from diagnostic FNA smears or paraffin embedded FNA derived cells, from 25 NSCLC patients of Indian origin, using the optimised protocols. Following successful DNA extraction from all patient samples, EGFR mutation status was determined by both DNA sequencing and using the therascreen EGFR Mutation Test Kit (L858R and exon 19 deletion mutations only). Twelve of the 25 patients harboured an EGFR mutation. For this sample type, the therascreen EGFR Mutation Test Kit was more effective at identifying mutation positive patients with only 4 of 12 detected mutations also evident by DNA sequencing. DNA extracted using a spin column based kit and quantified by real time PCR prior to performing molecular analysis gave the most robust, reproducible results. In conclusion, these data suggest that diagnostic FNA smears or cell blocks are suitable for assessing EGFR mutation status of NSCLC patients and may prove a useful source of tumour material when biopsies are unavailable. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3065. doi:10.1158/1538-7445.AM2011-3065