Risk factors for prostate cancer
The three most important risk factors are age, race and having a family history of prostate cancer. Many other risk factors, including lifestyle, diet and hormonal factors, are being investigated in ongoing epidemiological research projects. As with breast and colon cancer families, clustering of cases of men with prostate cancer has been reported frequently. However, at least some familial aggregation is due to increased prostate cancer screening in families thought to be at high risk.
Genetic risk factors for prostate cancer
One of the most important and well-researched risk factors for prostate cancer is family history. Having a first-degree relative (e.g. a brother or father) with prostate cancer increases the risk of prostate cancer to approximately twice that for men in the general population (Edwards and Eeles, 2004). The risk is inversely related to the age of the affected relative. Therefore the younger a man is diagnosed, the greater the risk to his relatives, with the risk being increased fourfold for cases diagnosed before the age of 60. An analysis of a Swedish database reported that the cumulative (absolute) risks of prostate cancer amongst men in families with two or more affected relatives were 5, 15 and 30% by the ages of 60, 70 and 80, respectively, compared with 0.45, 3 and 10% at the same ages in the general population. The risks were higher still if the affected father was diagnosed before the age of 70. Furthermore, there is a higher risk in black men, who have a 2.87-3.19-fold increased risk compared with white men in the UK (Ben-Shlomo et al., 2008). Interestingly, Lichtenstein et al. (2000) found that there is an increased risk in monozygotic rather than in dizygotic twins, supporting the hypothesis that genetic factors play an important role in the development of prostate cancer. Furthermore, aggressive disease is also known to have a heritable component (Hemminki et al., 2008).