A review by Abraham et al. addressed major topics in the epidemiology of prostate cancer (114). Blacks in the USA have the highest mortality rates in the world for this cancer. They are followed by whites in Norway, Switzerland, and Sweden. The lowest mortality rates occur among Asians in Singapore, Japan, and Hong Kong. However, the incidence of prostate cancer has been rising in Japan, where major dietary changes have occurred in the last 30 y. Further, the incidence of the disease is positively correlated with that of other diet-related cancers and is much higher in Japanese immigrants to Hawaii. Studies on the relationships between prostate cancer and intake of fats and vitamin A and carotenoids are summarized in text and tables. Although evidence for an adverse effect is supported by limited animal data. For effects of β-carotene, other carotenoids, or fruits and vegetables, the data are equivocal. A protective effect of carotenoids is seen principally in the context of a low – fat diet; it is also possible the some fruits contain risk-enhancing factors. Reports of a link between cadmium and cancer risk pertain mostly to occupational exposure. In sufficient data are available on other dietary components.
Rates of prostate cancer are very low in third World countries in populations that maintain a traditional lifestyle, but they rise in urban populations where lifestyles are in transition (115). Information on risk factors for these populations is meager; neither smoking nor alcohol consumption seems to be involved. A case-control study among blacks in Soweto, South Africa, found that high consumption of fat, meat, or eggs increased risk, were as high consumption of fruits or vegetables was protective. Specific foods that afforded protection were carrots, cabbage, and spinach; dietary fiber was also protective. Employment in an occupation that permitted ready access to a Western diet increased risk. No associations were seen for anthropometry, education, social class, smoking, and drinking.
A case-control study in northern Italy identified high milk consumption as a significant risk factor for prostate cancer (116). This agrees with most previous reports. Surprisingly, however, no consistent associations were found for cheese or butter intake, other sources of animal fat, of total fat.