Introduction: 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.
Methods: 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.
Results: 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.
Conclusion: Bronchoscopic uMS (biopsy needle rinsed fluids) are useful for multiple genetic examinations in NSCLC.