Molecular profiling of thin-prep FNA samples in assisting clinical management of non-small-cell lung cancer

The discovery of new target treatments for NSCLC has led to a search for new genetic and epigenetic markers able to selectively predict response to these new drugs. Somatic mutations in EGFR and KRAS genes are routinely analyzed to predict response to tyrosine kinase inhibitors (TKIs), used in the treatment of NSCLC patients, whose efficacy depend on the presence or the absence of specific mutations. MicroRNA (miRNA) expression evaluation has been recently analyzed because of the involvement of these molecules in lung cancer pathogenesis and in drug resistance. Only 30 % of NSCLC patients present a resectable stage at time of diagnosis so tissue samples cannot be the only starting material for genetic and epigenetic analysis. Therefore, the possibility to use cytological sampling already used for diagnosis also for molecular testing is emerging. The aim of this study was to evaluate for the first time in lung cancer the use of liquid-based cytology both for EGFR and KRAS mutational testing and for the expression trend of some miRNAs involved in lung cancer pathogenesis: miR-21, miR-155, miR-7, and let7a. We enrolled 20 fine-needle aspirate (FNA) samples diagnosed as NSCLC, 10 FNAs without neoplastic cells, and tissue samples coming from 5 of the 20 patients who underwent surgery after FNA NSCLC diagnosis. All Thin-Prep processed FNA samples were evaluable for DNA and RNA analysis and results were compared with those of the small group of patients whose matched tumor histology was available. The mutational status of the EGFR and KRAS genes and the expression profile of the selected miRNA showed comparable results between FNA samples and histological tissues. Our results underline that cytological samples could give the same genetic information as that obtained from histological specimens and so could be collected to create a nucleic acids bank.