Correlation of epidermal growth factor receptor (EGFR) mutation, immunohistochemistry (IHC), and fluorescence in situ hybridization (FISH) in esophageal squamous cell carcinoma (ESCC)

Abstract

4085 Background: ESCC remains a devastating cancer in Southern Thailand and novel therapeutic approach needs to be explored. EGFR tyrosine kinase (TK) inhibitor is a potential therapeutic agent against EGFR-expression tumors including ESCC. Forty-nine percent of ESCC patients in our institution overexpressed EGFR protein and 15% had EGFR gene amplification as published previously. Mutations within EGFR TK domain, particularly in exon 19 and 21, EGFR amplification or polysomy, and EGFR overexpression on IHC have all been associated with sensitivity and benefit to EGFR inhibitor treatment. To our best knowledge, no data on EGFR mutations in ESCC have been reported. This prompted us to perform analysis of EGFR mutations and correlate the status of each of these characteristics in ESCC. Methods: We studied 35 patients with ESCC whose data on EGFR IHC and FISH were available. DNA extraction was performed using a QIAamp DNA Kit. PCR for EGFR detection, using the oligonucleotide primers for amplification of exon 19 and 21, was sequenced and analyzed, using ABI Prism 377 sequencing analysis system and the Big Dye Terminator V3.0 Ready Reaction Cycle Sequencing Kit (ABI Prism). Results: Among 35 ESCC specimens evaluated, no EGFR somatic mutations in exon 19 or 21 were detected. Conclusions: EGFR mutations in exon 19 and 21 of ESCC were not identified in this study. EGFR overexpression and amplification do not correlate with EGFR mutation in Thai patients with ESCC. A clinical study of an EGFR inhibitor in esophageal carcinoma has been going on in our institution and the molecular markers as predictive factors need to be further evaluated and correlated with treatment outcome. No significant financial relationships to disclose.