Lung cancer is a type of cancer that begins in the lungs. Your lungs are two spongy organs in your chest that take in oxygen when you inhale and release carbon dioxide when you exhale. If a doctor identifies a suspicious lesion on a lung cancer screening, or a person is experiencing symptoms that could indicate lung cancer, several diagnostic tests are available to confirm the next steps. Treatment of lung cancer can involve a combination of surgery, chemotherapy, targeted therapy, immunotherapy, and radiation therapy as well as newer experimental methods. The general prognosis of lung cancer is poor because doctors tend not to find the disease until it is at an advanced stage.