For more than 25 years, epidemiologic studies have reported on the relation of dietary fat to the risk of prostate cancer. Indeed, fat per se, or food sources of fat, has probably been the most studied of all dietary factors with regard to this cancer site. Despite this extensive investigative effort, the role of dietary fat in prostate cancer remains unclear.

The hypothesis that dietary fat increases the risk of prostate cancer grew out of early ecologic studies that showed a positive correlation between prostate cancer mortality and per capita intake of fat, meat, and milk in international comparisons (1, 2). These findings were consistent with the recognition that prostate cancer risk is modifiable, as evidenced by such observations as the changing incidence and mortality rates in Japanese migrants to Hawaii and the substantial variations in incidence among ethnically similar populations in different geographic locations, eg, Chinese men in different countries of Asia and the United States (3, 4).