Endobronchial ultrasound in lung cancer with normal mediastinum: beyond the clinical guidelines

BACKGROUND: In patients with non-small cell lung cancer (NSCLC) and no evidence of mediastinal nodal metastases on positron emission tomography integrated with computed tomography (PET-CT), practice guidelines recommend that endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) should be performed when primary tumor is >3 cm in diameter, or centrally located and in radiological N1 disease. Our aim was to analyze the factors associated with “occult” N2/N3 mediastinal involvement in patients with normal mediastinum on PET-CT (N0/N1).METHODS: Retrospective analysis of a prospectively collected single center database that included consecutive patients with final diagnosis of NSCLC with non-pathological mediastinum on PET-CT who underwent EBUS-TBNA for mediastinal staging was conducted. The following variables were related to “occult N2/N3” disease: age, sex, histological type, lymph node size by EBUS, primary tumor (central/peripheral), anatomical location of the primary tumor, size of the primary tumor, SUVmax by PET of the primary tumor and lymph node stations, and nodal staging (N0 or N1).RESULTS: One hundred ten patients were included, 22 (20%) were upstaged to N2/N3 disease, diagnosed by EBUS-TBNA in 18 (81.8%). It was only associated with primary tumor >3 cm in diameter and centrally located (OR=3.26 [1.10-7.57] P=0.02).CONCLUSIONS: Occult N2 was identified in about a quarter of patients, increasing the risk when at least two clinical guidelines requirements are met rather than each one individually. So, until a robust and reliable prediction model is developed, EBUS-TBNA should be performed in the majority of patients, regardless of the primary tumor’s features.