Your genes and prostate cancer

We are what we are as a result of the genetic load we inherit from our parents, our grandparents and all the generations that have preceded us. In recent years there have been many analyses of the possible role of genetics in the development of cancers. A number of studies have also looked at the family histories of patients with prostate cancer to ascertain whether any of their relatives have developed the disease. In these studies details of the patients’ family histories have been put together and extensively analysed to establish the significance of inheritance as a possible cause of prostate cancer.

There appear to be two sets of patients:

In the first group, there is a very strong hereditary predisposition to the disease. Patients whose genome carries a mutation in the BRCA genes are highly likely to develop the disease.

In the other group, there does seem to be a less highly correlated but nevertheless slightly higher overall chance of developing the disease if the father of other close male relatives suffered the disease. One of the largest studies was carried out in Canada at the Laval University and published in 1995. 7,277 men with prostate cancer were questioned, and a family history of prostate cancer was obtained in only a small number of cases. Just 103 men had brothers who had developed prostate cancer, and 56 men had fathers who had had the illness, implying that genes are not significant in the development of prostate cancer. That is, out of a sample of over 7,000 men, only 159 had a positive family history. This is very unlike the situation for many other cancers. The evidence produced by this study shows that if your father was affected by the disease, the relative risk of your getting prostate cancer is increased 1.2-fold. Should a brother be affected, the risk is increased 2.6-fold. Although this increase may seem significant, it is important to note that this risk only applies to a very small number of men: out of over 7,000, only 2% had a family history of prostate cancer.