Detecting EGFR Mutations in Patients with Non-small Cell Lung Cancer

Abstract

Mutations in the receptor of the epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) are used as biomarkers for predicting the response of treatment with EGFR tyrosine kinase inhibitors (EGFR TKIs). Non-small cell lung cancer patients usually have activating EGFR mutations that leads to a very good response when they are treated with EGFR TKIs. Our tumor samples were examined for the presence of sensitive mutations in the EGFR gene, resistant mutations or the absence of mutations. To identify the types of the mutation, we used a real-time polymerase chain reaction (RT-PCR) method. Additionally, we evaluated the frequency of EGFR mutations and their association with smoking status, gender and histology. The tumor samples (n = 551) were tested for 29 somatic mutations in the EGFR gene. Sensitive mutations in the EGFR genes were found in 55 NSCLC samples (10.0%). The prevalence of EGFR mutations was much higher for females than for males (27.1 vs. 3.9%, p <0.001). The prevalence of EGFR mutations was greater in subjects who had never smoked than in smokers (15.0 vs. 6.08%, p <0.003). Additionally, the frequency of EGFR mutations was higher in adenocarcinomas than in other histological types (14.9 vs. 5.1%; p <0.001). Our results show that activating mutations on the EGFR gene are more frequent in females than in males, in adenocarcinoma than other histological types and in non smokers than smokers.

Keywords: Adenocarcinoma; Epidermal growth factor receptor (EGFR); Mutations; Non-small cell lung cancer (NSCLC); Real-time polymerase chain reaction (RT-PCR); Target therapy.

Figure 1

Plot shows EGFR positive samples for the exon 19 deletion; amplification of the internal control (Ctrl assay) with C_T 26.45 and amplification for mutational assay (del assay) with C_T 29.42. ΔC_T = 2.97 (calculated by the formula ΔC_T = mutation C_T-control C_T). The ΔC_T cutoff value for this mutational assay was 9.06.