EGFR mutational status of primary Lung Adenocarcinoma in an Indian cohort based on 2015 WHO classification of lung tumors

Abstract

Background: Epidermal growth factor receptor (EGFR) mutations have been known to be associated with adenocarcinoma, women, non-smokers and East-Asian ethnicity. This study was aimed to characterize the frequency of EGFR mutations and their association with histologic subtypes in primary lung adenocarcinoma in an Indian cohort. Methods:Two seventy-four cases were categorized using 2015 WHO classification of lung tumors. The frequency of each histologic subtype and cell type was correlated with EGFR exon sequences in a subset of 120 cases using polymerase chain reaction (PCR) gene sequencing. Results:The predominant biopsy categories in 274 cases were acinar 167(61%), solid 63(23%), mucinous 19(7%), lepidic 11(4%) and others 14(5%). EGFR mutations were detected in 49/120 (40.8%) including 3/5(60%) lepidic, 4/9(44.4%) papillary, 29/68(42.7%) acinar, 10/24(41.7%) solid and 1/13(7.7%) mucinous subtypes and were significantly associated with the cuboidal cell type (p=0.01). These mutations were common in women and non-smokers, although not statistically significant. Exon 19 mutations predominated in 36/49(73.4%). The majority, 213/263 (81%), were thyroid transcription factor 1(TTF-1) positive. The polygonal cell type and the solid subtype were frequent amongst stage IV tumors and smokers.Conclusions: EGFR mutations were most frequently seen with the lepidic and papillary subtypes, not associated with the mucinous subtype, more common in women and non-smokers and significantly associated with the cuboidal cell type.