EGFR direct sequencing on TBNA samples

Recent study have shown the superiority of treatment with gefitinib or erlotinib in lung tumors positive for EGFR mutation. In 75% of cases the diagnosis of lung cancer is performed on cytology specimens; there is the need to obtain a complete and reliable molecular diagnosis on cytologic specimens. TBNA allows the sampling of mediastinal lymph node for diagnosis and staging purposes. The aim of this study is to demonstrate that direct sequencing of exons 19 and 21 of EGFR in lung tumors, carried out on the cytological samples obtained through TBNA, is as reliable as the same analysis carried out on a histological surgical sample obtained from the same subject. We considered 50 patients with a histologic diagnosis of lung adenocarcinoma, whose cytological samples obtained by TBNA and histological samples obtained by surgical resection were available. A comparison of the sensitivity and reliability of the molecular biology analyses carried out on histological and cytological samples of the same patient will be carried out. The percentage of mutation of exons 19 and 21 of EGFR was 10%. The results of the analyses carried out on TBNA cytological samples matched those obtained from the histological samples. The feasibility of EGFR analysis on TBNA samples has already been demonstrated in previous studies, however these studies referred to the method of fluorescence in situ hybridization (FISH), or did not make any comparison between histological samples from the same patient; our work, on the other hand, shows that direct sequencing of exons 19 and 21 of EGFR gene can be performed also on TBNA cytological samples with the same reliability offered by the histological samples obtained from the same patient.