Definition: Lung cancer is a type of cancer that originates in the lungs. The lungs are like two “sponges” in the chest cavity, taking in oxygen when you breathe in and releasing carbon dioxide when you breathe out. Lung cancer is the leading cause of cancer death in both men and women in the United States. Lung cancer kills more people each year than colon, prostate, ovarian and breast cancers combined. Smoking is the most important risk factor for lung cancer. The risk of lung cancer increases with the duration of smoking and the number of cigarettes smoked. If you quit smoking, even after years of smoking, you can significantly reduce your chances of developing lung cancer. In its early stages, lung cancer usually does not cause signs and symptoms. It is usually only when lung cancer has progressed to an advanced stage that signs and symptoms appear. Signs and symptoms of lung cancer include: 1. new onset of cough that does not go away; 2. change in chronic cough or “smoker’s cough”; 3. hemoptysis, even in small amounts; 4. shortness of breath; 5. chest pain; 6. shortness of breath; 7. hoarseness; 8. weight loss without deliberate weight loss; 9. bone pain; 10. Headache.