In a previous study, we investigated the probability of developing cancer in the entire life span of a Japanese using population-based cancer incidence data from 1994, to obtain a relevant index of the impact of cancer occurrence on the Japanese population (APJCP, 1: 333-336, 2000). In the present paper, we have updated the information using the latest reports on cancer incidence in Japan in 1998. A method based on the cumulative risk of cancer was employed to estimate the probability of developing cancer up to 84 years of age, the average life expectancy of a Japanese female, and 79 years of age, the average life expectancy of a Japanese male. The time trend was also analyzed from 1975-1998. The cumulative risk of developing cancer in any site up to 84 and 79 years of age was 45% and 36% for males, 27% and 21% for females, and 35% and 28% for both genders, respectively. The cumulative risk showed an increasing time trend before leveling-off after 1985. From our results, it is expected that nearly onethird of Japanese males and one-fourth of Japanese females will develop cancer by the time they reach the average life expectancy.
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