Epidermal Growth Factor Receptor Inconsistency by Immunohistochemistry Method Using Different Monoclonal Antibodies in Colorectal Cancer Patients

BACKGROUND: Targeted therapy is typically used to treat colorectal cancer (CRC). The epidermal growth factor receptor (EGFR) was recognized as a potential therapeutic target. Does the EGFR protein express consistently using different monoclonal antibodies in clinics? METHODS: One hundred and sixty-four patients (mean age 61.80 ± 12.78 years) who suffered from CRC were selected at Mackay Memorial Hospital in Taiwan. Formalin-fixed and paraffin-embedded tissue sections from all patients were tested simultaneously using two commercial antibodies, Dako-EGFR (mouse monoclonal anti-EGFR clone 2-18C9, pharmDx) and NCL-EGFR (NCL-EGFR-384, Novocastra) monoclonal antibodies, to study the commutability or equality of the qualities of EGFR expression by standard immunohistochemistry (IHC) procedures. RESULTS: The EGFR expressions that were obtained by IHC staining using different monoclonal antibodies with Dako-EGFR (46.95%) and NCL-EGFR (32.32%) were fairly concordant. CONCLUSIONS: Although IHC is a convenient and feasible method for detecting the expression of EGFR, it yields controversial staining results concerning EGFR expression using various commercial antibodies in a CRC tumor section.