Correlation of epidermal growth factor receptor mutation, immunohistochemistry, and fluorescence in situ hybridization in esophageal squamous cell carcinoma.

BACKGROUND: The epidermal growth factor receptor (EGFR) has become a promising target for novel anticancer therapy Evaluation of its biological profiles including gene mutation, amplification, and protein expression in esophageal squamous cell carcinoma (ESCC) is essential to establish the EGFR molecular feature(s) suitable to select patients in anti-EGFR therapy. MATERIAL AND
METHOD: The subjects' specimens of ESCC at Songklanagarind Hospital were obtained and investigated for EGFR protein expression and gene amplification. Polymerase chain reaction (PCR) was performed to amplify the EGFR DNA product. The mutational status of EGFR exons 19 and 21 was analyzed using direct sequencing. The entire biological profiles of the EGFR were then correlated.
RESULTS: There were 48 eligible ESCC specimens. No somatic mutation in the tyrosine kinase domain of EGFR was detected A high level of EGFR protein was exhibited in 22 patients (46%). Twenty-three patients (48%) had shown a high gene copy numbers. However, no direct correlation between EGFR protein and gene status was observed.
CONCLUSION: EGFR mutations in the tyrosine kinase domain of exons 19 and 21 were absent in ESCC, whereas, protein overexpression and gene amplification was prevalent. Therefore, selection of ESCC patients for studies with anti-EGFR agents based on protein expression or gene copy number, not gene mutation, is rational.