Lung cancer forms in tissues of the lung, usually in the cells lining air passages. The two main types of lung cancer are small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).  SCLC is the more aggressive type, often found in small early-stage tumors and is harder to treat.  NSCLC is more common and can be further divided into subtypes adenocarcinoma and squamous cell carcinoma. Risk factors include smoking, exposure to radon and other airborne carcinogens. Early detection and treatment are crucial for improving outcomes.