EGFR mutation genotyping and ALK status determination in liquid-based cytology samples of non-small cell lung cancer

Personalised medicine for primary lung cancers (PLCs) requires molecular analysis of cancer tissue or cells. The primary objective of the present prospective study was to assess the concordance between epidermal growth factor receptor (EGFR) gene mutation detection and echinoderm microtubule-associated protein-like (EML) 4-anaplastic lymphoma kinase protein (ALK) expression using liquid-based cytology (LBC) samples and matched histology samples of PLC patients. A total of 117 patients who underwent surgical resection of non-small cell PLC were enrolled. Cytological specimens scratched from the resected PLC lesion were fixed in CytoRich Red. DNA extracted from LBC samples was examined for EGFR gene mutations. Anaplastic lymphoma kinase arrangement was analysed by immunostaining and fluorescence in situ hybridisation. Our patient cohort comprised 93 cases of adenocarcinoma, 16 squamous cell carcinoma, three adenosquamous carcinoma, two large cell neuroendocrine carcinoma, one pleomorphic carcinoma and two other cases. Sixty-six (58.4%) LBC samples harboured EGFR gene mutations. The overall concordance rate in EGFR gene mutation status, including minor mutations, between histologic and paired LBC specimens (N = 105) was 100%. The overall concordance rate of EGFR gene mutation status, including minor mutations and ALK status according to immunostains between histologic and paired LBC specimens, was 100% (105/105) and 100% (48/48), respectively. Genotyping and protein expression studies can be reliably performed using LBC samples prepared with CytoRich Red. Analysis of such samples may guide individual therapy in PLC patients.