Staging lung cancer: role of endobronchial ultrasound

Accurate staging is the first step in the management of lung cancer. Nodal staging is quite important for physicians to be able to judge the primary operability of patients harboring no distant metastasis. For many years, mediastinoscopy has been considered a “gold standard” modality for nodal staging. Mediastinoscopy is known to be a highly sensitive procedure for mediastinal staging and has been performed worldwide, but is invasive. Because of this, clinicians have sought a less invasive modality for nodal staging. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a minimally invasive modality for diagnosis and staging of lung cancer. EBUS-TBNA is a needle biopsy procedure that has accessibility compatible with the reach of the convex-probe EBUS scope, so N1 nodes are also assessable. The diagnostic yield is similar to that of mediastinoscopy, and the core obtained by the dedicated needle biopsy can be used for histological assessment to determine the subtypes of lung cancer. The samples can also be used to test for various biomarkers using immunohistochemistry, polymerase chain reaction for DNA/complementary DNA, and in situ hybridization, and the technique is useful for selecting candidates for specific molecular-targeted therapeutic agents. According to the newly published American College of Chest Physicians guideline, EBUS-TBNA is now considered “the best first test” for nodal staging in patients with radiologically suspicious nodes. Appropriate training and thorough clinical experience is required to be able to perform correct nodal staging using this procedure.