Men who are lifelong smokers have a 16 percent chance of dying of lung cancer by age 75, and those who smoke more than 25 cigarettes a day have a 24 percent chance. Quitting smoking at age 50 reduces the risk of dying of lung cancer to 6 percent for men, effectively cutting it by more than half. Quitting at age 30 lowers the chance of dying of lung cancer to 1.7 percent, which is still higher than that of people who've never smoked, but far less than that of people who continue to smoke until age 75. For example, men who smoke five or fewer cigarettes a day for a lifetime have a 10 percent chance of dying of lung cancer by age 75. That is one of the great strategic mistakes in tobacco control, I think.
Lung cancer is just one of numerous diseases that smoking can cause.
However, it is the most dreaded one because it is almost always fatal within a year or two of diagnosis. In the United States, about 157,000 people will die of the disease this year. In 1990, smoking contributed to 170,000 cancer deaths, including throat, bladder and lung cancer, and to 290,000 deaths from other diseases, for a total of 460,000.