Purpose: Epidermal growth factor receptor (EGFR) mutations are prerequisites for the targeted therapy with anti-EGFR tyrosine kinase inhibitors (TKIs) in non-small-cell lung carcinomas (NSCLCs). In patients with advanced-stage NSCLC, sometimes cytological specimens, including those from fine-needle aspiration cytology (FNAC) and pleural effusion, are the only materials for mutation analysis. The purpose of this study was to compare the results of EGFR mutation detection from cytological specimens and histological samples and to evaluate the difference between them, therefore to assess if cell block is a valid source for detection of EGFR mutation.
Methods: Forty-seven samples from advanced-stage NSCLCs were obtained with individually matched cell blocks (CBs) from FNAC (29 cases) or pleural fluid (18 cases), and formalin-fixed paraffin-embedded (FFPE) blocks from biopsy (34 cases) or surgical excision (13 cases). CBs and FFPE blocks were simultaneously tested for EGFR hot mutations in exons 18, 19, 20 and 21 by polymerase chain reaction (PCR)-direct sequencing and amplification refractory mutation system (ARMS)-PCR.
Results: EGFR mutations were identified in 18/47 (38.3%) or 21/47 (44.7%) cases using CBs and 16/47 (34.0%) or 19/47 (40.4%) using FPPE blocks by PCR-direct sequencing or ARMS-PCR, respectively. The incidence of EGFR mutation was not statistically significant between CBs and FFPE blocks using PCR-direct sequencing or ARMS-PCR (p=0.668 or p=0.677, respectively).
Conclusion: Our study suggests that cytological specimens are optimal for advanced NSCLC. The successful use of these non-invasive specimens in molecular pathology is beneficial for patients requiring targeted therapy.