Quantitative relationship between cumulative cigarette consumption and lung cancer mortality in Japan

Background Sufficient evidence has been accumulated to demonstrate the causal relationship between cigarette smoking and lung cancer risk. Therefore, the lung cancer risk of a country is supposedly determined by the amount of cigarettes consumed in the country, but this quantitative relationship has yet to be clarified at a national level. Objective To find the quantitative relationship between cigarette smoking and subsequent lung cancer risk at a national level. Methods The quantitative relationship between cigarette smoking and lung cancer mortality is formulated as a function of cumulative cigarette consumption. The formulae for ages 25–29 to 70–74 are estimated by examining the increment of the lung cancer death rate in relation to the unit increase in cumulative cigarette consumption in different birth cohorts. The validity of the quantitative relationships is then examined by comparing lung cancer deaths expected from the formulae with observed deaths in past studies. Results Cumulative cigarette consumption was found to have increased in later birth cohorts for all ages of males and females. The age-specific lung cancer death rates from 35–39 to 70–74 were found to increase in proportion to cumulative cigarette consumption. Comparison of the results with past studies showed good agreement. Conclusion The change over time in the lung cancer death rate of males and females in Japan can be explained fairly well by the increase in cumulative cigarette consumption at the national level.