Prof. Richard Doll will be widely remembered for just one thing: as the man who proved that smoking causes lung cancer. He & his colleagues have taken 50 years to complete the study, but his work bears comparison with the greatest discoveries of the modern age.Because the detrimental effects of smoking are largely self-inflicted, & because 90% of lung cancers are caused by smoking,Doll's work amounts to a cure.Doll proved that an early age of smoking is associated with an overall increased risk of lung cancer.The final report was with comparative mortality rates between smokers and non-smokers.Men born between 1900 and 1930, who smoked only cigarettes & continued smoking throughout their lives,died on average about 10 years younger than lifelong non-smokers.Those who gave up at age 60, 50, 40 or 30 years gained, respectively, about three, six, nine or 10 years of life expectancy.Cessation at age 50 halved the risk of contracting lung cancer,& stopping at 30 avoided almost all of it. The studies also exposed the extent to which smoking hastened the onset of many other fatal diseases. Indeed, lung cancer accounted for less than half of the comparatively early mortality among smokers.