Endobronchial ultrasound-guided fine-needle aspiration for pulmonary carcinomas genotyping: Experience with 398 cases including rapid EGFR/KRAS analysis in 43 cases

Background: Endobronchial ultrasound-guided fine-needle aspiration (EBUS-FNA) of mediastinal lymph nodes is a minimally invasive and efficient tool for both diagnosis and staging of lung cancer. EBUS-FNA also permits tumor genotyping. However this critical datum for the therapeutic management is often long to obtain for metastatic patients with short life expectancy. Methods: From May 2011 to December 2017, 398 lung cancer patients underwent a genetic analysis based on EBUS-FNA samples. EBUS-FNAs were performed with rapid on-site evaluation. Mutations were studied with Sanger or new generation sequencing. Forty-three cases were also tested with a fully automated real-time PCR rapid technique. ALK abnormalities were assessed by immunohistochemistry and/or in situ hybridization. Results: A genotypic result could be obtained in 316 cases (79.4%) and in 180 of the 198 more recent cases (90.9%). Genetic abnormalities were observed in 191 cases (48.0%). Using the rapid technique, EGFR/KRAS mutational status was obtained within a few hours following the histological diagnosis and on the same day of the EBUS-FNA by analyzing fresh specimens after intra-operative cytological diagnosis. Conclusions: In term of molecular diagnosis, EBUS-FNA provides high-quality biological material similar to that of other clinical sampling methods. Furthermore, our study suggests that a rapid molecular diagnostic method could lead to a prompt and appropriate therapeutic management for many advanced stage patients.