The association between cigarette smoke and disease is direct; cigarette smoking is a major cause of disease in the United States. More than 400,000 people die each year as a result of cigarette smoke. Smoking is responsible for almost 90% of all cases of lung cancer. Smoking cessation reduces the risk of lung cancer within five years. Cessation also may reduce the risk of other cancers, such as cancer of the head and neck, pancreas, and esophagus. Smoking causes skin wrinkling and sexual dysfunction, which can be mediated by smoking cessation. Even after a diagnosis of cancer, smoking cessation improves the odds of survival and reduces the risk of developing a second cancer.