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.
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 the 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.
The results of this study clearly imply that our genes have very little to do with the development of prostate cancer. This fact comes as a relief for many men who receive a positive diagnosis, because they know that the risk of passing the disease on to their sons is not significantly increased.
There is a theory that an underlying genetic propensity to cancer can be sparked by exposure to an environmental agent, whether chemical or viral, and this causes the cancer to develop. This theory has many protagonists. However, with prostate cancer all the evidence seems to point to environmental causes for the disease.
