Non small cell lung cancer (NSCLC) accounts for most lung cancer cases and includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. It often develops silently, so many patients are diagnosed at an advanced stage. Cigarette smoking is the leading risk factor, but air pollution, occupational exposures, and genetic susceptibility also contribute.

Diagnosis combines imaging with tissue biopsy, followed by detailed molecular testing. Beyond traditional staging by tumor size, lymph node involvement, and metastasis, classification now relies on specific genetic alterations such as EGFR, ALK, ROS1, BRAF, MET, RET, NTRK, and KRAS. These biomarkers guide increasingly personalized therapies.

Targeted therapies have transformed treatment for patients whose tumors carry actionable mutations. Tyrosine kinase inhibitors directed at EGFR, ALK, and other drivers can produce high response rates and delay progression, although acquired resistance is common. Newer generation inhibitors are being developed to overcome resistance mutations and improve activity in the brain.

Immunotherapy has become a key pillar of treatment, especially agents that block PD 1 or PD L1. These drugs reinvigorate immune responses against cancer and can yield long lasting control in a subset of patients. PD L1 expression and tumor mutational burden help predict benefit, but not perfectly.

Radiotherapy and surgery remain crucial, especially for early stage disease, often combined with chemotherapy or immunotherapy before or after surgery. Current research emphasizes integrating targeted drugs and immunotherapy, optimizing treatment sequencing, managing resistance, and refining biomarkers to match each patient with the most effective, least toxic strategy.