• endoscopic ultrasound
• mediastinum
• fine needle aspiration
• lung cancer

Mediastinal involvement either by direct invasion or by spread to lymph nodes is seen at diagnosis in up to 50% of patients with non-small cell lung cancer and has a significant impact on both treatment and prognosis. Ipsilateral or subcarinal lymph node involvement (N2 disease) is associated with a 5 year survival of 7–13%¹ and usually precludes resection, but may identify a subset of patients who might benefit from neoadjuvant therapy. Contralateral nodal disease (N3) is surgically incurable with fewer than 5% of patients surviving 5 years. Accurate assessment of the mediastinum at the time of diagnosis is therefore vital for patients deemed suitable for potentially curative treatment.

To date, computed tomographic (CT) scanning remains the mainstay of imaging the mediastinum but it has limited sensitivity and specificity for detecting nodal involvement. Enlarged benign reactive nodes are frequently present in patients with a lung primary and, conversely, micrometastasis may exist in “normal” sized nodes.^2,3 Thus, the finding of nodes greater than 1 cm on CT scanning usually leads to mediastinoscopy or anterior mediastinotomy to obtain histological proof of involvement. These procedures are invasive, require general anaesthesia, and have a small (1–3%) complication rate. Mediastinoscopy alone may also provide limited access to the subcarinal space and posterior mediastinum. By contrast, in 10–12% of patients with apparently negative preoperative CT scans, mediastinal nodal disease is discovered at operation.³

Endoscopic ultrasound (EUS) is a technique which has been in clinical practice …