African-Americans' Risk
African Americans have a higher rate of prostate cancer, but why, is not clear. Several factors have been suggested, including genes, diet, and hormone levels. It is most likely due to an interaction among all three. One thing that makes it difficult to break down the genetic part from the environmental part is the lack of data on cancer rates in Africa.
There is evidence, however, that African American men may be exposed to higher levels of testosterone over the course of their lives. This would likely increase the incidence of prostate cancer because cumulative exposure to testosterone (more specifically its product, DHT) seems to be a key factor in its development. Young African American men have been shown to have about 15% higher levels than do Caucasians the same age. Diet also seems to play a role. African Americans appear to consume more fat in their diets than Caucasians, and dietary fat has been suggested, although not conclusively, to increase the risk of prostate cancer. The genetics of prostate cancer are not well understood, but some research suggests that the testosterone/DHT hormone receptors in African Americans may be more active than in Caucasians or Asians, thus increasing the influence of hormones. Last, there is some evidence that access to care may play a role in the differing prostate mortality rates. African American men are, on average, diagnosed at a later stage when their cancer may no longer be curable. This is another reason why African American men should be encouraged to undergo screening beginning at about age 40-45.
