title: Differences in the influence of tobacco smoking on lung cancer between Japan and the USA: possible explanations for the 'smoking paradox' in Japan.
abstract: OBJECTIVE
  The prevalence of cigarette smoking among Japanese men has been consistently high compared with males in Western countries over the past 30 years. However, during the same period, the incidence and mortality rates for lung cancer have been consistently lower in Japan than in Western countries, which has been termed the 'Japanese smoking paradox'. The odds ratio/relative risk of cigarette smoking for lung cancer mortality and incidence for the same number of cigarettes smoked per capita in Japan have been lower than those in Western countries. This difference in the odds ratio/relative risk is likely to be the main reason for the Japanese smoking paradox. The aim of this study was to clarify the reason for the difference in the odds ratio/relative risk between Japan and the USA.
  
  
  METHODS
  Literature review to compare environmental, hereditary and other factors that may be related to lung cancer in Japan and the USA.
  
  
  CONCLUSIONS
  The main factors likely to have brought about the difference in the odds ratio/relative risk between Japan and the USA (and perhaps other Western countries as well) are: lower alcohol consumption by Japanese males; lower fat intake by Japanese males; higher efficiency of filters on Japanese cigarettes; lower levels of carcinogenic ingredients in Japanese cigarettes; and lung-cancer-resistant hereditary factors among Japanese males.
authors.affiliation: Department of Social Medicine, Hirosaki University Graduate School of Medicine, 036-8562 Aomori, Japan.
authors.forename: Ippei
authors.initials: I
authors.lastname: Takahashi
authors.forename: Masashi
authors.initials: M
authors.lastname: Matsuzaka
authors.forename: Takashi
authors.initials: T
authors.lastname: Umeda
authors.forename: Kiyonori
authors.initials: K
authors.lastname: Yamai
authors.forename: Miya
authors.initials: M
authors.lastname: Nishimura
authors.forename: Kazuma
authors.initials: K
authors.lastname: Danjo
authors.forename: Terumi
authors.initials: T
authors.lastname: Kogawa
authors.forename: Kumiko
authors.initials: K
authors.lastname: Saito
authors.forename: Maki
authors.initials: M
authors.lastname: Sato
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Nakaji
mesh_terms: D000428:Alcohol Drinking / Q000453:epidemiology / Q000208:ethnology; D003466:Cultural Characteristics; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000208:ethnology; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology* / Q000208:ethnology; D014481:United States / Q000453:epidemiology