Do you know what cancer is the deadliest? Lung cancer kills more people than any other cancer and by a landslide. According to the American Cancer Society and National Cancer Institute, 1.37 million cancer deaths are attributed to lung cancer every year, responsible for 26 percent of women’s cancer deaths and 29 percent of men’s cancer deaths. The next most deadly cancer may be surprising to many, however. Cancers of the stomach causes 736,000 deaths each year. The World Health Organization estimates there will be a total of 13.1 million cancer deaths a year by 2030.