New Endoscopic Ultrasound (EUS) Applications in Lung Cancer: Evaluation of Patients With Negative Mediastinal CT and Re-Staging After Neoadjuvant Treatment

The main purpose of staging in non-small cell lung cancer (NSCLC) is to assess mediastinal lymph node involvement, with thoracic CT being the main non-invasive test for this. However, given that up to 15% of patients who show no mediastinal lymph node involvement in the CT has lymph node metastasis during surgery, other examinations are required. Endoscopic ultrasonography guided fine-needle aspiration (EUS-FNA) was shown to be able to detect advanced disease (metastatic mediastinal lymph nodes, adrenal metastasis, mediastinal invasion by the tumor) in approximately 25% of patients with a CT that suggested a non-advanced disease.Another situation in which CT has a very limited value is in the evaluation of the response to induction therapy, with its most limiting factor being its intrinsic inability to distinguish between a tumor and necrosis. In this context, EUS-FNA was shown to have a good performance, with a sensitivity, negative predictive value and precision of 75%, 67%, and 83%, respectively.In conclusion, EUS-FNA may be considered a good alternative in the pre-operative staging of patients with NSCLC, with and without diseased mediastinal lymph nodes in CT, and could play an important role in the mediastinal re-staging of these patients by identifying a patient sub-group who might benefit from additional surgical treatment.