Lung cancer refers to several different types of cancer which begin in the linings of the lungs. Lung cancer is currently the deadliest cancer, killing 1.3 million people per year. The five-year survival rate for lung cancer is less than 15%. Fortunately, however, lung cancer is also one of the most easily prevented of the major cancers. By far the most significant risk factor for lung cancer is tobacco use, including cigarette smoking.