Explanations for the smoking paradox in Japan.

The prevalence of cigarette smoking among Japanese men has been consistently high compared with Western males over the past 30 years. However, during the same period, the incidence of and mortality rates for lung cancer have consistently been lower in Japan than in Western countries ('Japanese smoking paradox'). The odds ratio/relative risk of cigarette smoking for lung cancer mortality/incidence relative to the same number of cigarettes smoked per capita in Japan, were apparently lower than those in Western countries. This must be the cause driving the 'Japanese smoking paradox'. Furthermore, low carcinogenic ingredients in Japanese cigarettes and a congenitally-related resistance to smoking-related lung carcinogenesis emerged as the main factors which have brought the 'Japanese smoking paradox'.