Prediction of male lung cancer mortality in Japan based on birth cohort analysis.

The future trend in male lung cancer mortality in Japan was predicted by using a simulation model. The model was based on the age-specific death rates from lung cancer in males by birth cohort, expressed as Fi(t) = rkSitr-1 exp(-ktr). The parameters in the function were obtained from the mortality data in Vital Statistics (1960-1980). The chi-square test for goodness-of-fit supported the statistical validity and acceptability of the function. Extrapolation of the function provided future age-specific death rates by birth cohort for males in Japan. In this simulation model it was possible to evaluate the effects of preventive strategies and/or therapeutic improvements on lung cancer mortality when five additional parameters were taken into consideration. According to this model, the age-adjusted death rate from lung cancer in Japanese males is predicted to increase linearly until the year 2000 and to level off thereafter. The total number of deaths from lung cancer for all Japanese males is predicted to be 27,000 in 1990 and over 40,000 in 2000. With the establishment of an effective preventive strategy for young generations, the mortality would begin to decrease a few decades later. Improvements in the therapy of lung cancer, if realized, might suppress the future upward mortality trend in Japan to some extent. The above simulation model based on birth cohort analysis should be useful in estimating the impact of developments in prevention and treatment of lung cancer as well as in predicting the future mortality trend.