EGFR mutation testing is the analysis of tumour DNA to detect mutations in the EGFR gene.
In patients with lung cancer, the DNA that codes for the tyrosine kinase domain of the EGFR protein may harbour a mutation which results in the production of a mutated EGFR protein
Effects of mutation
Mutations in the tyrosine kinase domain of the EGFR gene increase the activity of the intracellular signalling cascades
This results in the cells of the tumour becoming dependent on (“addicted to”) the EGFR signalling pathways for proliferation, invasion, survival and metastasis, stimulation of tumour-induced angiogenesis and the inhibition of apoptosis
Location of EGFR mutations
EGFR mutations are found in four exons of the EGFR gene, exons 18 to 21. Exon 19 deletions and a point mutation in exon 21, L858R, account for around 90% of all activating mutations
EGFR-positive mutations are present in approximately 30-50% of East Asian and approximately 10% of North American and Western European patients with non-small cell lung cancer
The diagram below shows mutation types and incidence. Further information is available here Sharma 2007
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