Endosonography in mediastinal staging of lung cancer: a concise literature review

The endoscopic assessment of the mediastinal status has become extremely widespread in the last two decades due to its safety and efficacy. While in patients with known/suspected advanced lung cancer sampling of the mediastinal lymph nodes is often carried out as the diagnostic success of endosonography is higher than that of guided bronchoscopy aimed at sampling a peripheral primary tumor, in patients with potentially operable disease a thorough mediastinal staging is key for therapeutic decision-making. While imaging studies such as computed tomography (CT) and F-18-fluoro-deoxy-glucose positron emission tomography (FDG-PET) are commonly used as first step approach in patients with suspected lung cancer, their diagnostic accuracy is insufficient and a tissue diagnosis is usually required to confirm or rule out reliably the metastatic involvement of hilar or mediastinal lymph nodes. The aim of the present review is to describe the role of endosonography [endobronchial ultrasound (EBUS); esophageal ultrasound (EUS)] in the mediastinal staging of lung cancer. Besides the rationale, equipment, and indications for endosonography in this setting, more controversial issues such as the staging strategy ("hit and run" versus systematic staging"), the role of the endosonographic staging in certain categories of patients with cN0 lung cancer, the importance of a surgical staging after a negative endosonographic evaluation, and the current means of risk stratification will be briefly discussed.