Molecular epidemiology of epidermal growth factor receptor mutations in lung cancers in Indian population

Abstract

Background: Lung cancer is the leading cause of cancer related mortality world-wide and amongst males in India. The discovery of tyrosine kinase inhibitors holds a ray of hope for a subset of lung cancer patients, which have activating epidermal growth factor receptor (EGFR) mutations. Much of the preliminary data on frequency of EGFR mutations emanated from Western studies, which reported EGFR mutation rates of 10-15%. However, studies from Asian countries report a much higher frequency of EGFR mutations, not only in the male population, but also in females. AIM: The object of this study was to share the author's experience of EGFR mutation testing in 402 lung cancer patients as no large-scale study addressing the issue has been published from India. Materials and Methods: Formalin fixed paraffin embedded tissues were analyzed for EGFR exon 19 deletions and exon 21 point mutation by length analysis of fluorescently labeled polymerase chain reaction products on Applied Biosystems Inc. 310 genetic analyzer. Results: Out of 402 samples, 35 samples could not be analyzed because of poor deoxyribonucleic acid material. Thus of the remaining 367 cases analyzed, EGFR mutations were found in 118 patients (32%). Mutations were equally distributed between males (50%) and females (50%). Majority of the mutations were seen in adenocarcinoma subtype (90%). Exon 19 mutations accounted for 76% while exon 21 mutations accounted for 24% of the mutations. Summary: EGFR mutation frequency is higher in Indian population vis-à-vis Caucasian population, but lower than that reported in the East Asian population. A significantly higher number of males also harbor EGFR mutations.