Lung cancer is a malignant tumor that can be categorized as small cell or non-small cell. Small cell lung cancer grows faster but is more responsive to chemotherapy. It can be limited, confined to the chest, or extensive, having spread outside the chest. Symptoms often appear after the cancer has invaded tissues or spread. Small cell lung cancer accounts for 20% of lung cancer cases and has a median survival of 16-24 months with treatment for limited stage disease. Risk factors include cigarette smoking and second-hand smoke exposure. Treatment depends on stage and typically involves chemotherapy and radiation.