Changing demography of prostate cancer in Asia

There has been a recent trend in Asia towards increasing incidence of prostate cancer, with some low-risk regions, such as Japan and Singapore, reporting a more rapid increase than high-risk countries. In this study, age-specific and age-standardised (world) incidence rates and mortality rates for prostate cancer in Asian countries for 1978-1997 were retrieved and compared. The results confirm that the incidence of prostate cancer has risen by 5-118% in the indexed Asian countries. Incidence at centres in Japan rose as much as 102% (Miyagi 6.3-12.7 per 100,000 person-years) whilst the incidence in Singaporean Chinese increased 118% from 6.6 to 14.4 per 100,000 person-years. The lowest incidence rate recorded was in Shanghai, China and the highest rates were in Rizal Province in the Philippines, although still much lower than those in the United States of America (USA) and many European countries. Whilst the absolute value of the increase is not comparable to North American and European populations, the incidence ratio in many Asian centres is similar to that of the high-risk countries. The mortality data for prostate cancer showed a similar rising trend. The increases in age-adjusted mortality rates per 100,000 person-years, adjusted to the world standard, ranged from 50% in Thailand to 260% in Korea. The difference may be partly due to genetic polymorphism in the androgen receptor and androgen metabolism pathway enzymes as well as to dietary or environmental factors. In particular, phytochemicals, such as isoflavonoids and tea polyphenols, which are common in Asian diets showed promising anti-mitotic activity in animal and clinical studies. In conclusion, with gradual Westernisation, many Asian countries may be losing their cultural protective factors and acquiring high-risk ones. A better understanding of how these factors interact to cause prostate cancer through further studies with a multi-ethnic perspective will facilitate appropriate public health strategies to minimise high-risk factors and maintain protective factors and keep prostate cancer at bay.