EGFR Mutant test is a genetic test used to detect mutations in the EGFR (Epidermal Growth Factor Receptor) gene. The EGFR gene plays an important role in regulating cell growth and division. Mutations in the EGFR gene can lead to uncontrolled cell growth, contributing to the development of cancer. This test is often used to diagnose and monitor non-small cell lung cancer. The test results help doctors determine if the patient will respond to EGFR-targeted therapies. These therapies are often used to treat non-small cell lung cancer with EGFR mutations.