Lung cancer is now the number one killer of men in the United States. And the number one killer of women is lung cancer. A new study shows that lung cancer can be prevented by taking a lung cancer drug. The drug, known as pemetrexed, is used to treat lung cancer. It has been shown to be effective in preventing the spread of the disease. The study, published online in the New England Journal of Medicine, showed that pemetrexed can prevent more than half of all lung cancer deaths in men and women.