EGFR amplification

What it is

EGFR amplification is the presence of too many copies of the EGFR gene (epidermal growth factor receptor) in tumor cells. Because EGFR signals cells to grow, having excess copies drives tumor growth. In adult diffuse astrocytic gliomas, EGFR amplification is one of the molecular markers that can define glioblastoma.

Understanding EGFR amplification

The EGFR gene makes a receptor on the cell surface that, when activated, signals the cell to grow and divide. When the gene is amplified (present in many extra copies), the cell receives excessive growth signals, promoting aggressive tumor behavior. EGFR amplification is common in glioblastoma and is one of the three molecular markers (along with TERT promoter mutation and combined chromosome 7 gain and 10 loss) that classify an IDH-wildtype diffuse astrocytic glioma as glioblastoma even without the most aggressive appearance. EGFR has also been studied as a potential treatment target, though effective EGFR-targeted therapy for glioblastoma has been challenging to achieve. Understanding EGFR amplification clarifies a common growth-driving marker that can define glioblastoma.

Why it matters

Understanding EGFR amplification helps patients and families see one of the molecular markers used in diagnosis — an excess of a growth gene that drives glioblastoma and can define it even before the most aggressive appearance develops.