Lung cancer is the leading cause of cancer deaths in Malaysia. There are two main types of lung cancer, and small cell lung cancer has four stages. Tobacco smoking is the main cause of lung cancer, responsible for 60-70% of cases. Lung cancer can be detected through tests like chest x-rays, CT scans, and biopsies. Treatment options include surgery, chemotherapy, radiation therapy, and targeted drug therapies. While smoking is a major risk factor, lung cancer can also be caused by factors like genetic mutations and exposure to radon gas or other air pollutants.