Is EGFR expression important in non-small cell lung cancer?

Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase, is frequently overexpressed in non-small cell lung cancer (NSCLC). These receptors play an important role in tumour cell survival and activated phosphorylated EGFR results in the phosphorylation of downstream proteins that cause cell proliferation, invasion, metastasis, and inhibition of apoptosis. Expression appears to be dependent on histological subtypes, most frequently expressed in squamous cell carcinoma but also frequently expressed in adenocarcinomas and large cell carcinomas.¹ Not surprisingly, there are many published reports attempting to correlate the relationship between EGFR protein overexpression and survival. However, the data regarding the prognostic role of EGFR expression are inconsistent and confusing, with some reports indicating that EGFR is associated with poor survival while no prognostic association was seen in other reports.

In this issue of Thorax Nakamura et al carried out a meta-analysis of 18 studies (including nearly 3000 patients), reviewing whether EGFR overexpression has an impact on survival. Most of these reported studies evaluated EGFR protein expression by immunohistochemistry (IHC) and it is possible that different conclusions may reflect differences in incubation and detection methods, reagents, assay cut off points, and population studied with different stages. Nevertheless, EGFR overexpression was seen in 39% in adenocarcinoma, 58% in squamous cell carcinoma, and 38% in large cell carcinoma, and they concluded that EGFR protein overexpression using …