Epidermal growth factor receptor in colorectal carcinoma: correlation with clinico-pathological prognostic factors

This study was undertaken to determine the relationship between epidermal growth factor receptor (EGFR) status in primary colorectal cancer (CRC) to different clinico-pathological prognostic factors. Seventy-nine primary CRC were studied using four scoring systems: 1- EGFR pharmDx score, 2- score modified from the Hercept test [J Histo cytochem, 52 (2004) 893], 3- two additive scores with different cutoff points [Mod Pathol, 11 (1998) 155], 4- two multiplicative scores with different cutoff points [Ann Oncol, 16 (2005) 102]. More than 10% membranous EGFR reactivity was identified in 46.8% (37/79) of the tumours. The intensity was classified as mild, moderate and strong representing 8.9%, 20.3% and 17.7% respectively. Strong correlation was found between the EGFR pharmDx and the proposed scores, at different cutoff points (P < 0.01). A strong correlation was found between EGFR expression, advanced clinical stage (P < 0.01), nodal involvement (P < 0.01) and lympho-vascular invasion (LV) (P < 0.05) in category I factors, poorly differentiated tumours in IIA (P < 0.05), infiltrative border configuration in IIB (P < 0.01), perineural invasion (PN) in III (P < 0.01), and larger tumours in IV (P < 0.01). Heterogenous staining was present in 46.3% of tumours and was associated with an increased score, LV and PN invasion and advanced clinical stage (P < 0.05). Using a cut-off point of 10%, similar results with different scoring systems were obtained, representing standardization for EGFR interpretation. EGFR expression is correlated with conventional clinico-pathological prognostic factors.