Smoking cigarettes increases a person's risks for not only lung cancer, but also cancer of the stomach, mouth, throat, kidney, cervix, pancreas and bladder. And 40 percent of the premature deaths in the United States that result from smoking in a given year are from cancer [source: National Cancer Institute]. The good news is that quitting will improve a person's health no matter how long he or she smokes. The idea that a lifelong smoker might as well keep smoking just doesn't hold up. An ex-smoker who has gone without a cigarette for five years has reduced his risk of lung and oral cancer by a full 50 percent [source: National Cancer Institute]. Ten years after quitting smoking, that same ex-smoker has the same risk of contracting lung cancer as someone who has never smoked a cigarette [source: University of Florida].