EBUS and EUS guided fine needle aspirations for molecular diagnostic analysis in lung cancer

In daily clinical practice the diagnosis of lung cancer is often based on cytological specimens. These cytological samples are increasingly obtained by ultrasound-guided techniques with fine needle aspirations. Recent developments have shown that transesophageal ultrasound guided fine needle aspiration (EUS-FNA) and endobronchial ultrasound guided transbronchial fine needle aspiration (EBUS-TBNA) are minimally invasive diagnostic and staging procedures that have shown to be highly sensitive and accurate. Although several studies have shown that these cytological samples allow for reliable diagnosis and sub classification of non-small cell lung cancer, cytological samples for molecular analysis are not yet routinely used. In this paper we review the current literature regarding the results of molecular analysis of samples obtained by EUS-FNA and/or EBUS-TBNA, focusing on the targets for currently available treatments of non-small cell lung cancer like epidermal growth factor receptor (EGFR), Kirsten rat sarcoma oncogene (KRAS) and Echinoderm microtubule-associated protein-like 4 gene anaplastic lymphoma kinase gene translocation (EML4-ALK). We conclude that the cytological samples obtained by endosonography guided fine needle aspirations (EUS and EBUS) are highly accurate for molecular analysis. This analysis can be performed reliably in the vast majority of patients in daily practice.