Prevalence and outcome of epidermal growth factor receptor mutations in non-squamous non-small cell lung cancer patients

BACKGROUND: Epidermal growth factor receptor (EGFR) mutation analysis has become an important part of the initial workup of non-squamous non-small cell lung cancer (NS-NSCLC) patients as it is now recognized both as a prognostic and predictive marker to therapy with EGFR tyrosine kinase inhibitors (TKI). AIM: In this retrospective study conducted at a University hospital, we evaluated the prevalence of EGFR mutations in patients with NS-NSCLC, clinico-pathological correlation and outcome to treatment with EGFR TKIs. MATERIALS AND METHODS: Case records of 147 patients of NS-NSCLC in whom EGFR mutation status was tested were screened. EGFR mutation analysis was done using DNA sequencing by real time polymerase chain reaction method from tissue and cell blocks prepared from core biopsy, fine needle aspiration cytology and pleural fluid specimens. RESULTS: EGFR mutations were seen in 30.6% of the 111 evaluable specimens, with a significantly higher rate in females (44% vs 19.6% P = 0.0072) as compared to men and non-smokers (41% vs 12% P = 0.0013) as against smokers. Most common mutations were observed in exons 19 (71%) and 21 (25%). The estimated median progression free survival for patients with and without mutations when treated with upfront TKIs was 12 months and 3 months respectively and the estimated median overall survival for patients with and without mutations was 20 and 9 months respectively. CONCLUSION: This study from India, further establishes the importance of upfront EGFR mutation testing in all NS-NSCLC patients, not only to prognosticate, but also to identify that subset of patients who could benefit from EGFR TKI therapy, early in the course of their disease.