Although genetic information is essential for molecular targeted therapy for personalized medicine, tissue sampling for genetic analysis remains challenging. We investigated the utility of bronchoscopic sampling in non–small-cell lung cancer (NSCLC) patients compared with conventional histological materials for multiple genetic analyses.
Patients with NSCLC proven by onsite cytological evaluation during bronchoscopic survey were eligible for this study. After conventional needle aspiration biopsy by flexible bronchofiberscopy of primary lesions or convex-probe endobronchial ultrasound of lymph nodes, the used needle was rinsed with saline, and the ultra-microsample (uMS) was used for cytological diagnosis and genetic analysis. Gene mutations and fusion genes were examined by high-resolution melting analysis and direct sequencing. The results from the uMS and those from conventional histological samples were compared.
A total of 134 lesions (48 primary and 86 metastatic) were analyzed. Adenocarcinoma (n = 80), squamous-cell carcinoma (n = 43), and NSCLC (n = 11) samples were pathologically confirmed in histological cores; however, malignancies were detected in only 45 (34%) of the corresponding uMS. In 62 samples, genetic disorders, including epidermal growth factor receptor (n = 21), K-ras (n = 11), and BRAF mutations (n = 1); anaplastic lymphoma kinase (n = 5), receptor tyrosine kinase (n = 1), and RET fusion genes (n = 1); and silent mutations (n = 22), were identified. In total, 1474 molecular tests were performed, and 1464 tests (99.3%) were identical for both histological samples and uMS.
Bronchoscopic uMS (biopsy needle rinsed fluids) are useful for multiple genetic examinations in NSCLC.