Epidermal growth factor receptor (EGFR) gene amplification in high-grade gliomas: Western Indian tertiary cancer center experience.

Abstract

EGFR gene amplification is the hallmark of primary glioblastomas; however, its frequency in patients of Indian origin remains sparsely investigated. The aim of this study was to explore the frequency of EGFR amplification in high grade gliomas (HGGs) in Indian patients and to study its correlation with p53 protein overexpression. 324 cases of HGGs, where EGFR gene amplification was evaluated by fluorescence in-situ hybridization formed the study group. Ratio of >2 was considered as EGFR gene amplification. Immunohistochemically, p53 overexpression was evaluated and graded as positive for strong intensity staining in more than 50% of tumour cells. 249 patients were male and 75 female (M: F-3.3:1); their age range was 8-91 years [paediatric glioblastoma (pGBM; 8-18yrs; n = 24)], adult HGGs [>18yrs; n = 300]}. 258 patients were having a GBM [including 31 with a GBM with oligodendroglioma component (GBM-O)], 31 with a gliosarcoma, 13 with an anaplastic astrocytoma (AA), 12 with an anaplastic oligodendroglioma (AO), and 10 with an anaplastic oligoastrocytoma (AOA). 79/233 cases (34%) with an adult GBM, (including 10/31 with a GBM-O [32.2%]), 1/31 (3.2%) with a GS and 1/10 (10%) with an AOA showed EGFR gene amplification. None of the pGBMs (n = 24) showed amplification. Amplification was seen in 19/81 (23.4%) of diffuse p53 protein positive cases and 53/143 (37%) of cases with focal or negative p53 protein expression. 34% of our adult GBM patients showed EGFR gene amplification. The amplification was uncommonly associated with a strong diffuse p53 protein expression.