Molecular analysis of EGFR gene in different types of tumor material from NSCLC patients.

Lung carcinoma is the most frequently occurring cancer worldwide and the Non-small Cell Lung Cancer (NSCLC) subtype represents 80% of all diagnosed cases. Epidermal growth factor receptor (EGFR) has an important dual role in NSCLC patients. On one hand, EGFR is frequently mutated in many types of tumors, which leads to deregulation of important downstream pathways including those affecting cell proliferation, differentiation and migration. On the other hand, presence of certain activating mutation leads to increased sensitivity of EGFR to tyrosine kinase inhibitors (TKIs) treatment. Detection of these mutations is essential for identification of NSCLC patients who would profit from such therapy. However, due to the nature of available tumor material and the relatively high number of mutation hot spots, such DNA analysis may be challenging and time consuming. Here we present an approach combining direct sequencing and SNaPshot assay for identification of EGFR mutations in FFPE tissues as well as in rarely analyzed cytological smears. Using this strategy on the set of 450 tested NSCLC samples; we have identified 29 activating mutations and 14 variants, which might be interesting in predicting the efficiency of TKI therapy.