Epidermal growth factor receptor positive non-small cell lung cancer

Epidermal growth factor receptor–positive non-small cell lung cancer is a molecularly defined subtype of epithelial lung malignancy characterized by activating mutations or alterations in the *EGFR* gene Affecting primarily the respiratory system, this subtype is most commonly identified in non-squamous histology—predominantly lung adenocarcinoma—and occurs with greater frequency in females, individuals of Asian descent, and patients with light or never-smoking histories

Epidermal growth factor receptor–positive non-small cell lung cancer is a molecularly defined subtype of epithelial lung malignancy characterized by activating mutations or alterations in the *EGFR* gene Affecting primarily the respiratory system, this subtype is most commonly identified in non-squamous histology—predominantly lung adenocarcinoma—and occurs with greater frequency in females, individuals of Asian descent, and patients with light or never-smoking histories

Pathophysiologically, oncogenic alterations such as exon 19 deletions or the exon 21 L858R substitution cause constitutive autophosphorylation of the EGFR tyrosine kinase domain This sustained receptor activation triggers downstream signaling pathways, including MAPK and PI3K/Akt, driving uncontrolled cell proliferation, survival, angiogenesis, and metastatic dissemination

Pathophysiologically, oncogenic alterations such as exon 19 deletions or the exon 21 L858R substitution cause constitutive autophosphorylation of the EGFR tyrosine kinase domain

This sustained receptor activation triggers downstream signaling pathways, including MAPK and PI3K/Akt, driving uncontrolled cell proliferation, survival, angiogenesis, and metastatic dissemination