OSNA: A Fast Molecular Test Based on CK19 mRNA Concentration for Assessment of EBUS-TBNA Samples in Lung Cancer Patients.

Background: Lung cancer is the major cause of cancer death worldwide. Mediastinal lymph node staging is important for pretreatment lung cancer management. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a well established method for mediastinal lymph node staging. Although EBUS-TBNA samples are much smaller than surgical lymph node biopsies, histopathological evaluation and molecular testing can successfully be performed. One step nucleic acid amplification (OSNA), which measures cytokeratin 19 (CK19) mRNA concentration, is a target marker that is gaining importance in quick detection of lymph node metastases in breast cancer and other cancers. Recent publications suggest accurate and rapid detection of lung cancer metastases in surgically removed lymph nodes. In this study we aimed to investigate if CK19 mRNA detection via OSNA is feasible to accurately detect lymph node metastases in lung cancer patients using EBUS-TBNA samples.

Materials And Methods: A total of 102 EBUS-TBNA samples of 55 patients were collected. EBUS-TBNA was performed in lymph nodes exceeding 5 mm. OSNA was performed using a ready to use amplification kit (Lynoamp; Sysmex, Kobe, Japan) in the RD-100 I, an automated real-time detection system (Sysmex).

Results: Histopathological analysis confirmed malignancy in 90 cases and excluded malignancy in 12 cases. Overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 78.9%, 58.3%, 93.4%, 26.9%, and 76.5%, respectively.

Conclusions: One step nucleic acid amplification is feasible for EBUS-TBNA lymph node samples of lung cancer patients, but CK19 mRNA is an inaccurate marker, which is unlikely to be useful as an adjuvant test for EBUS-TBNA. Further studies are required to define the optimal sample size and sampling method.