EGFR Mutation in Cancer
OncogeneEpidermal Growth Factor Receptor
EGFR is a tyrosine kinase receptor that drives cell proliferation when activated. Activating mutations in EGFR are key therapeutic targets in non-small cell lung cancer with multiple approved inhibitors.
What Is EGFR?
EGFR (Epidermal Growth Factor Receptor) is a transmembrane tyrosine kinase receptor that, when activated by ligands such as EGF and TGF-alpha, triggers intracellular signaling cascades including RAS/MAPK, PI3K/AKT, and STAT pathways. These pathways control cell proliferation, survival, migration, and differentiation. Oncogenic EGFR mutations cause ligand-independent receptor activation, driving uncontrolled tumor growth.
EGFR Mutations in Lung Cancer
EGFR mutations are most clinically significant in non-small cell lung cancer (NSCLC), where they occur in approximately 15-30% of cases (higher in never-smokers, women, and East Asian populations). The two most common activating mutations are exon 19 deletions (~45%) and the L858R point mutation in exon 21 (~40%). Together, these "classical" EGFR mutations predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs). The T790M mutation is the most common resistance mechanism to first- and second-generation TKIs.
Precision Medicine
EGFR testing is mandatory for all advanced NSCLC patients. Three generations of EGFR TKIs are approved: first-generation (gefitinib, erlotinib), second-generation (afatinib, dacomitinib), and third-generation (osimertinib), which also targets T790M resistance mutations. Osimertinib is now first-line standard of care for EGFR-mutant advanced NSCLC, with recent data supporting its use in adjuvant and neoadjuvant settings.
Morphological Patterns
EGFR-mutant lung adenocarcinomas show characteristic histological patterns: lepidic and papillary growth patterns are more common, while solid and micropapillary patterns (typically aggressive) are less frequent compared to KRAS-mutant tumors. HistoAtlas captures these morphological associations quantitatively, linking EGFR mutation status to measurable changes in tumor architecture, nuclear morphology, and immune infiltration patterns.
Frequently Asked Questions
What is an EGFR mutation?
An EGFR mutation is a change in the EGFR gene that causes the receptor to be continuously active, driving cell growth without normal regulatory signals. EGFR mutations are most important in lung cancer, where they occur in 15-30% of non-small cell lung cancers and predict response to targeted therapy.
What does EGFR positive mean?
EGFR positive (or EGFR mutation positive) means the tumor has an activating mutation in the EGFR gene, typically an exon 19 deletion or L858R mutation. This is significant because EGFR-positive lung cancers respond to EGFR tyrosine kinase inhibitors (TKIs) like osimertinib, offering better outcomes than chemotherapy alone.
How are EGFR mutations treated?
EGFR-mutant cancers are primarily treated with tyrosine kinase inhibitors (TKIs). Osimertinib (a third-generation TKI) is the current standard first-line therapy for EGFR-mutant advanced lung cancer. Earlier-generation TKIs (gefitinib, erlotinib, afatinib) are also used. Treatment choice depends on the specific EGFR mutation type.