This document discusses lung cancer, including its causes, symptoms, diagnosis, staging, and treatment options. The main causes of lung cancer are tobacco smoking and secondhand smoke. Symptoms can include cough, dyspnea, hemoptysis, and chest pain. Diagnostic tests include chest X-ray, CT scans, PET scans, and biopsies. Staging involves the TNM system and determines appropriate treatment such as surgery, chemotherapy, radiation therapy, or targeted therapies. Treatment depends on the cancer stage and may involve a combination of options.