Expression of epidermal growth factor receptor (EGFR) in colorectal cancer: An immunohistochemical study

The epidermal growth factor receptor (EGFR) plays an important role in tumourigenesis and tumour progression of colorectal cancer (CRC) and leads to the activation of intracellular signaling pathways. The use of anti-EGFR-targeted therapy has increased for patients with metastatic CRC. Today, the clinical utility of immunohistochemistry has remained somewhat inconclusive. It is based on EGFR screening methods using paraffin-embedded tumour specimen to select patients eligible for treatment. There is still lack of agreement on reproducible scoring criteria for EGFR immunohistochemistry has in various clinical trials.

We retrospectively reviewed 36 CRC patients who underwent surgeries during 2011 in Habib Thameur hospital in Tunis. We analyzed the immunohistochemical overexpression of EGFR using a score based on immunostaining intensity. In addition, we analyzed the correlation between this overexpression and patients' clinicopathologic parameters.

The positive expression rate of EGFR was 78% (28/36). Using the immunoreactivity score, 21 cases were considered low grade expression and 15 tumours were high grade. Immunohistochemical expression of EGFR showed a significant difference with tumour's location (p = 0.034) and vascular invasion (p = 0.03). This expression was not significantly associated with age, gender, tumour size, histological type, grade, TNM staging and perineural invasion.

EGFR expression by immunohistochemistry in CRC is variably correlated with clinicopathological parameters. Its assessment by this method has still not proved its predictive value.