Endobronchial ultrasound: from lung cancer diagnosis and staging to translational research

Ultrassom endobrônquico: do diagnóstico e estadiamento do câncer de pulmão até a pesquisa translacional Juliana Guarize Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is probably the most important advance in thoracic diseases in the last decade. EBUS-TBNA was first applied for the diagnosis of lymph node metastasis in lung cancer patients. Thereafter, its indications quickly evolved, and the method is currently used for the diagnosis of many thoracic diseases, including sarcoidosis, thymomas, tuberculosis, lymphomas, and metastatic diseases. In the oncological setting, EBUS-TBNA soon became a key tool in the evaluation of lung cancer patients. The uses of EBUS ranged from extended and bilateral mediastinal staging to the collection of specimens for molecular analyses—epidermal growth factor receptor (EGFR) mutations, KRAS mutations, and anaplastic lymphoma kinase (ALK) rearrangement—underpinning modern target therapy in lung cancer patients. In the diagnosis of peripheral pulmonary nodules or ground-glass opacities, EBUS-radial probe has improved the diagnostic yield of transbronchial biopsies and dramatically reduced the number of CT-guided transthoracic fine needle aspiration biopsies and their associated complications. Mediastinal staging is fundamental for the evaluation of resectable lung cancer and indicates the type of treatment (induction chemotherapy, surgery, or definitive chemotherapy/radiotherapy). For many years, mediastinoscopy was the gold standard for mediastinal staging and was widely used in referral centers. Currently, EBUS-TBNA equals mediastinoscopy in terms of its sensitivity and specificity for the diagnosis of mediastinal lymph node metastasis, and EBUS-TBNA has all of the advantages of a minimally invasive procedure. In 2011, we performed 79 mediastinoscopies for mediastinal staging of lung cancer patients. In 2012, after the introduction of EBUS into our clinical practice, the number of mediastinoscopies dropped to 17, confirming the central role of EBUS-TBNA at a cancer referral center. Rapid on-site evaluation (ROSE) and specimen handling are crucial to enhancing the diagnostic yield of EBUS-TBNA and to obtaining all mutational analyses in the final examination. At our center, specimens are collected with a 22G dedicated needle (NA-201SX-4022; Olympus, Tokyo, Japan) and a small amount of material is smeared onto glass slides. Some of the slides are air-dried and stained immediately using MGG quick stain (Bio-Optica, Milan, Italy) so that the cytopathologist can immediately interpret and confirm the adequacy of cell specimens. " Mirror " slides are alcohol-fixed for H&E staining. Other needle passages and sustained material are fixed into a formalin-like solution in order to be processed as a cell block for histological evaluation. In the last …