Feasibility of Bronchial Washing Fluid-Based Approach to Early-Stage Lung Cancer Diagnosis

A blood-based approach such as circulating tumor DNA remains challenging in diagnosis for early-stage disease. Bronchial washing (BW) is a minimally invasive procedure that yields fluids that may contain tumor DNA. Therefore, we prospectively enrolled 12 patients with early-stage non-small cell lung cancer without endoscopically visible tumors. Somatic mutations were analyzed using ultra-deep next-generation sequencing in 48 paired specimens (primary tumor tissue, normal tissue, BW supernatant, and BW precipitate). In primary tumors, 130 missense mutations/indels (5-16 per patient) and 20 driver mutations (0-3 per patient) were found. Concordance of driver mutations between BW fluids and primary tumors was 95.0%. The allele frequencies for missense mutations/indels in BW supernatants significantly correlated with those in primary tumors and were higher than those in BW precipitates. These findings suggest that BW supernatants are reflective of tumor-associated mutations and could be used for early-stage lung cancer diagnosis.