The Epidermal Growth Factor Receptor (EGFR) belongs to the ERBB receptor tyrosine kinase family, which includes EGFR (ERBB1), HER2 (ERBB2), HER3 (ERBB3), and HER4 (ERBB4). EGFR is a transmembrane protein with extracellular ligand-binding domains and intracellular tyrosine kinase activity domains, primarily expressed in epithelial cells. By binding specific ligands such as EGF, EGFR activates downstream signaling pathways including MAPK, PI3K/AKT, and JAK/STAT, regulating cell proliferation, differentiation, migration, and survival. The gene expression and mutations of EGFR exhibit tissue specificity and are closely associated with the occurrence and development of various cancers, particularly non-small cell lung cancer and colorectal cancer. EGFR mutations or overexpression are associated with cancer therapy resistance and poor prognosis.