Adequacy of EBUS-TBNA specimens for accurate therapeutic decision

T. Nemanic*^a (Ms), J. Srajner^a (Mr), V. Dimitric^a (Mrs), M. Marc Malovrh^a (Dr)

^a University Clinic of Respiratory and Allergic Diseases Golnik, Golnik, SLOVENIA

* tiva.nemanic@klinika-golnik.si

Background. EBUS-TBNA is due to minimal invasiveness and high accuracy an important diagnostic tool in patients with lung cancer (LC). Beside the role in mediastinal staging, it can also provide accurate molecular characterization of non-small cell LC in majority of patients with nonresectable or metastatic disease. Our aim was to find out the accuracy of EBUS-TBNA lymph node specimens, obtained from our patients, for a full assessment including immunohistochemistry (IHC) and molecular tests when indicated.

Methods. We retrospectively analysed 78 patients with LC in whom EBUS-TBNA of lymph nodes was performed as a diagnostic procedure from 2019-2021 at University Clinic Golnik. The decision which molecular tests were needed was made according to the current guidelines. Among mutations, EGFR and KRAS were tested first (PCR), if both negative, tests for ALK (IHC), and in case of negative ALK test, NTRK, ROS1 (FISH) and BRAF (PCR) followed.

Results. The final diagnosis was small cell LC in 17, adenocarcinoma in 47, squamous cell carcinoma in 5 and non-determined non-small cell LC in 6 patients. EBUS-TBNA was diagnostic in 75 (96.2%) patients, and provided adequate tissue for PD-L1 testing in 79.2%, EGFR and KRAS in 96.2%, ALK in 84,6%, ROS1 in 92%, NTRK in 88%, BRAF in 81.5% of specimens in which selected testing was indicated. In 14 (17.9%) patients further procedure for optimal therapeutic decision was needed.

Conclusion. Our data show that EBUS-TBNA provided adequate specimens for therapeutic decision in majority of patients (82.1%), with high success rates in mutational status detection, and a place for improvement in adequacy of samples for PD-L1 assessment.

Disclosure of funding source(s): none