Detection of an EGFR mutation in cytological specimens of lung adenocarcinoma

Epidermal growth factor receptors (EGFR) mutation status is crucial for the prediction of a tumour response to treatment with EGFR tyrosine kinase (EGFR-TK) inhibitors. The aim of the study was to establish a protocol for the detection of EGFR-activating somatic mutations on cytological samples collected using a standard bronchoscopy procedure and to determine the frequency of EGFR mutations among pre-selected Croatian patients with non-small cell lung cancer (NSCLC) of an adenocarcinoma histological subtype.

A total of 177 cytological samples were collected from the patients diagnosed with NSCLC. DNA was isolated from the cytological material recovered from the fixed and stained slides. EGFR mutations were analysed using the polymerase chain reaction (PCR)- mediated Sanger sequencing method.

Out of 177 collected samples, EGFR mutation analyses were successfully performed on 167 samples (94.4%); 77 (46.1%) of these were from male and 90 (53.9%) from female patients. EGFR mutations/deletions were found in 33 (19.8%) of the tested patients; exon 19 deletions in 17 (10.2%) and point mutations of exon 21 in 16 (9.6%) patients.

The PCR-mediated Sanger sequencing method was found to be reproducible and reliable. Cytological samples can be used successfully to determine the EGFR mutation status in NSCLC patients providing information for targeted therapy at an early stage of the disease.