EGFR gene mutation study in cytology specimens

Activating mutations of the epidermal growth factor receptor (EGFR) gene in non-small cell lung cancer predicts a significantly higher clinical response rate to tyrosine kinase inhibitors targeting EGFR, and it is currently recommended that patients under consideration for EGFR TKI as first-line therapy be tested for such mutations to determine the appropriateness of treatment. For lung cancer patients who present with advanced stage disease where surgical treatment is not indicated, cytology specimens obtained through bronchoscopy, drainage of body fluid, or fine-needle aspiration are the only means to obtain tumor cells for tissue diagnosis and EGFR gene mutation testing. We reviewed the experience of 1,410 consecutive EGFR mutation testing requests at a single institution in Hong Kong that comprised 269 cytology specimens and 1,141 surgical specimens. The material inadequacy issue in cytology specimens may be overcome by tumor cell enrichment strategies and employment of mutation detection techniques with increased analytical sensitivity. The use of cytology specimens to test for predictive molecular cancer biomarkers is without a doubt expected to increase, and cytopathologists should be closely engaged with the clinicians in the therapeutic process and become acquainted with new technology in order to directly participate in personalized oncology care.