Genetic analysis of EGFR mutations in non-small cell lung carcinoma: A tertiary care center experience

Abstract

Background: In the past decade, the association of epidermal growth factor receptor (EGFR) mutations with response to tyrosine kinase inhibitor gefitinib has revolutionized the treatment of lung adenocarcinomas. The research done in the West has suggested an association of EGFR mutation with factors such as female sex, nonsmoker status, and adenocarcinoma. Aim: This study was aimed to find the prevalence of EGFR mutations in lung cancer in the Indian population and its association with clinicopathological parameters. Materials and Methods: Sixty cases of non-small cell lung carcinoma (NSCLC) were studied histomorphologically and immunohistochemically for EGFR protein expression and for EGFR gene mutations by sequencing. The statistical analysis was done by calculating P value using Chi-square test. Results: Statistically significant relation of adenocarcinoma with female sex and nonsmoker status was noted. EGFR mutations were seen in 30% of NSCLC and 70% of lung adenocarcinoma cases. Statistically significant relation of EGFR mutations with female sex, nonsmoker status, and adenocarcinoma histology, particularly of the bronchioloalveolar type was noted. No relation of EGFR mutation with the age of the patient and the stage of the tumor was observed implying that EGFR mutation is an early event in the pathogenesis of lung adenocarcinoma. Exon 19 deletions were the most common type of EGFR mutations, with a higher prevalence in the male patients. Exon 21 and 18 mutations were also observed, particularly in females. No relation between EGFR mutations by sequencing and EGFR protein expression by immunohistochemistry was observed. Conclusion: In the Indian population, the prevalence of EGFR mutations in NSCLC is higher than that in the West, and it is associated with female sex, non-smoker status, and adenocarcinoma. Exon 19 deletions are the most common type of EGFR mutations. Immunohistochemistry for EGFR does not correlate with EGFR mutations and cannot be used as its substitute for deciding gefitinib treatment.