Prostate cancer incidence was prospectively studied among 7999 men of Japanese ancestry who were first examined between 1965 and 1968 and then followed through 1986. During this surveillance period, 174 incident cases of prostate cancer were recorded. Prostate cancer was not associated with any measure of socioeconomic status, including amount of education, type of occupation, and type of residence. There was also no relationship with the number of children, as a surrogate measure of sexual activity. Increased consumption of rice and tofu were both associated with a decreased risk of prostate cancer, while consumption of seaweeds was associated with an increased risk of prostate cancer. There was no relationship between prostate cancer and the intake of various nutrients, including total fat and total protein. Etiological implications of these associations are discussed, but more research is needed on these dietary factors and the subsequent development of prostate cancer before any firm conclusions can be drawn.
This investigation was supported by USPHS Grant RO1 CA 33644, awarded by the National Cancer Institute, NIH, Bethesda, MD.