Objective: The aim of this study was to investigate epidermal growth factor receptor (EGFR) gene mutations and anaplastic lymphoma kinase (ALK) gene rearrangements using cytological specimens from the patients with a diagnosis of primary or metastatic lung non-small cell carcinoma.
Materials and methods: A total 307 cases were submitted for EGFR mutational analysis and 265 cases for ALK analysis. The cytological specimen sources included lung, lymph node, liver, bone, adrenal gland, mesentery mass, and body fluids/bronchial brushing. EGFR mutations in the exons 18 to 21 were analyzed with Qiagen EGFR Pyro Kits. Fluorescence in situ hybridization (FISH) studies for ALK rearrangement inv(2)(p21; p23) were performed on the paraffin-embedded cell block sections utilizing dual-color Vysis LSI ALK Break Apart Probe Kit.
Results: Among 307 fine needle aspirate cases for EGFR analysis, 302 cases (269 from cell blocks, 33 from direct smears) had sufficient material for EGFR test. Five cases failed due to inadequate cellularity. Twenty six of 302 (8.6%) cases were positive for EGFR mutations. A total of 265 cases submitted for ALK analysis included 240 cases of fine needle aspirate, 25 cases of pleural fluid/pericardial fluid/bronchial washings. Eight cases failed because of low cellularity, whereas 257 of 265 cases had sufficient material for ALK FISH study. Nine of 257 cases (3.5%) revealed ALK rearrangement by FISH.
Conclusions: The current study demonstrates that cytological specimens can yield sufficient material for EGFR mutations and ALK rearrangement test. Our study reveals that 8.6% of EGFR mutation rate and 3.5% of ALK rearrangement rate in the cytology specimens from the patients with primary or metastatic lung non-small cell carcinoma.