EGFR mutation test by PCR
EGFR (Epidermal Growth Factor Receptor) is a receptor that plays a key role in regulating cell growth, division, and survival. It is a critical target for targeted therapies in several types of cancer. Mutations in the EGFR gene can activate downstream signaling pathways, promoting tumor development and metastasis. EGFR mutation testing supports personalized treatment and helps guide effective therapeutic strategies.
What is EGFR?
EGFR is a membrane-bound receptor that becomes activated upon binding with epidermal growth factor (EGF).
Once activated, EGFR initiates signaling cascades such as the MAPK (Mitogen-Activated Protein Kinase) and PI3K (Phosphoinositide 3-Kinase) pathways, promoting cell proliferation and survival.
Normally, this process is tightly regulated, but mutations in the EGFR gene can lead to uncontrolled cell growth and tumor formation.
Role of EGFR in Cancer
EGFR mutations can result in continuous activation of signaling pathways even in the absence of external stimuli, contributing to tumorigenesis. These mutations are most commonly associated with:
Lung cancer
- EGFR mutations are found in 10–20% of patients with non-small cell lung cancer (NSCLC), especially in non-smoking women with adenocarcinoma. Tumors with EGFR mutations are sensitive to EGFR inhibitors such as gefitinib, erlotinib, and afatinib.
Head and neck cancers
- EGFR mutations or overexpression can occur in squamous cell carcinoma, where EGFR contributes to tumor progression.
Breast cancer
- In some breast cancer cases, especially triple-negative types, EGFR overexpression is associated with aggressive disease.
Types of EGFR Mutations
Activating mutations:
- Most commonly found in exons 18–21, these lead to receptor hyperactivation and uncontrolled cell proliferation.
- T790M mutation: Associated with acquired resistance to first-generation EGFR inhibitors.
- EGFR amplification: Increased gene copy number leading to higher protein expression and enhanced pathway signaling.
Prognosis and Treatment
Lung cancer
- Patients with EGFR mutations often respond better to targeted therapies (e.g., gefitinib, erlotinib, osimertinib) than to conventional chemotherapy.
- T790M mutation: Indicates resistance to earlier treatments; second- or third-generation inhibitors like osimertinib may be effective.
Head and neck cancer
- EGFR expression can guide the use of cetuximab, a monoclonal antibody targeting EGFR.
Breast cancer
Overexpression of EGFR may indicate a need for more aggressive or targeted approaches.