EGFR mutation
Genetic alterations in the epidermal growth factor receptor gene that predict response to targeted therapy in lung cancer.
Full Definition
EGFR (epidermal growth factor receptor) mutations are specific genetic changes found in approximately 10-15% of lung adenocarcinomas in Western populations and up to 50% in East Asian populations. The most common mutations are exon 19 deletions and exon 21 L858R point mutations, which predict sensitivity to EGFR tyrosine kinase inhibitors like erlotinib, gefitinib, and osimertinib. Testing for EGFR mutations is standard practice in lung cancer workup as it directly impacts treatment decisions. The T790M resistance mutation may develop after initial treatment with first-generation EGFR inhibitors.
Usage
Usage note: Capitalize EGFR as an acronym; specify the type of mutation when known (exon 19 deletion, L858R, T790M).
In Context
- "Molecular testing revealed an EGFR exon 19 deletion, making the patient eligible for targeted therapy." — Oncology consultation note
- "The tumor was negative for EGFR mutations but positive for PD-L1 expression." — Pathology molecular report