Rates of Lung Cancer vs Smoking in Japan and the United States
Upon noting that there were more male smokers in Japan but a lower risk of lung cancer, researchers set out to make some comparisons. They found that the difference was not related to the amount of smoking. The men from the United States and those from Japan smoked for essentially the same number of years, and also averaged the same number of cigarettes daily.
Yet, while in the United States the "odds ratio" of lung cancer in male smokers vs non-smokers was 40.1 (in other words, male smokers were 40 times more likely to develop lung cancer than male non-smokers in the U.S.), the odds ration in Japan was 6.3. In other words, male smokers in Japan were only 6.3 times as likely to develop lung cancer as male non-smokers in Japan.