The utility of endosonography for mediastinal staging of non-small cell lung cancer in patients with radiological N0 disease

Abstract

Objectives: Recent practice guidelines recommend endosonography for patients with radiological N0 non-small cell lung cancer (NSCLC) when the primary tumors are >3 cm in diameter or centrally located. However, any role for endosonography remains debatable. We evaluated the utility of endosonography in patients with radiological N0 NSCLC based on tumor centrality, diameter and histology.

Materials and methods: Patients who underwent staging endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) with or without transesophageal bronchoscopic ultrasound-guided fine needle aspiration (EUS-B-FNA) for radiological N0 NSCLC were retrospectively investigated using prospectively collected endosonography data. The radiological N0 stage was defined by node diameter as evident on computed tomography images and ¹⁸F-FDG uptake using integrated positron emission tomography-computed tomography.

Results: In total of 168 patients, the median size of the primary tumor was 39 mm, and 41 % of tumors were centrally located. The prevalence of occult mediastinal metastases was 11.3 % (19/168). The sensitivity of endosonography in terms of diagnosing occult mediastinal metastases was only 47 % (9/19); 6 of 10 patients with false-negative endosonography data exhibited metastases in accessible nodes. The diagnostic performance of endosonography did not differ by tumor centrality or diameter. Patients with adenocarcinoma histology showed higher prevalence of occult mediastinal metastases and higher false-negative results in endosonography compared with those with non-adenocarcinoma histology.

Conclusion: Not all patients with radiological N0 NSCLC benefit from endosonography, given the low prevalence of occult mediastinal metastases and the poor sensitivity of endosonography in this population. The strategy of invasive mediastinal staging needs to be tailored considering the histology of the tumor in this population.

Keywords: EBUS; Endosonography; Mediastinal staging; Non-small cell lung cancer; Radiological N0 disease.