What Causes Lung Cancer?

The lungs are the organs responsible for exchanging oxygen and carbon dioxide in the blood before the heart pumps it back around the body. Lung cancer is the top cause of all cancer-related deaths in the United States. Cancer that develops in the lung tissue can be aggressive in local tissues, but also spreads easily via the lymphatic or circulatory systems. Symptoms of lung cancer include cough, wheezing, chest pain, breathlessness, hoarseness, repeated respiratory infections, difficulty swallowing, weight loss, fatigue, and coughing up blood.