Trends and characteristics in prostate cancer mortality in Japan

Background: In North America, the incidence and mortality of prostate cancer has been declining since the early 1990s. We calculated the age-adjusted death rates, age-specific death rates and standardized mortality ratio (SMR) for prostate cancer in Japan and analyzed their features. Methods: Yearly age-adjusted death rates for prostate cancer were calculated by dividing the number of events by the population at risk, with direct standardization to the world population. Age-specific death rates were calculated for the 1970s, 1980s and 1990s and which age group showed the highest rate of increase was examined. The SMR in each prefecture was also calculated for each period. Results: The respective number of deaths and the age-adjusted death rate was 1107 and 2.29 in 1973 and 6251 and 5.15 in 1997. The age-specific death rates showed an exponential increase with age in all three periods and the rate of increase was higher in older age groups. The distribution of SMR showed the same tendency in all three periods. The prefectures with significantly high or low SMR were distributed in clusters. Conclusions: The prostate cancer death rate is increasing rapidly in Japan. However, the age-adjusted death rate has remained stable from 1996 to 1997. How this figure will change and whether the prostate cancer death rate in Japan will begin to decline, like in North America, is of interest. The prefectures with significantly high or low SMR showed a characteristic clustered distribution pattern.