Relative with Prostate Cancer
Prostate cancer seems to run in families, especially if it was diagnosed before the age of 65. About 15% of men diagnosed with prostate cancer have a first-degree male relative (father or brother) who has had the disease, compared to about 8% of the total male population in the U.S. This involves nearly a doubling of the risk.
A 1997 study involving nearly 2,000 men who died from prostate cancer out of nearly 500,000 followed for 9 years confirmed this risk. The researchers found that, compared with men who have no family history of prostate cancer, having a father or a brother who was diagnosed under the age of 65 doubles a man's risk. The younger the age the relative was diagnosed, the more likely there is to be a genetic link. Nearly one-half of cases diagnosed in men under the age of 55 are related to genetic defects. The risk is somewhat less when the relative was diagnosed at an older age because it is less likely due to a genetic cause. Prostate cancer that develops later in life is more likely to be related to environmental causes. A greater number of relatives affected also increases the risk. If a man's father and brother have had the disease, the risk is tripled.
With a family history of prostate cancer, men tend to be diagnosed at a younger age, and at a more advanced stage than without a family history. This is why men with a family history are considered at high risk for prostate cancer and, therefore, may be advised to begin screening at a younger age, such as 40 or 45. The increased risk due to family history appears to be about the same in various ethnic groups.
The genetic defects involved in the development of prostate cancer are only beginning to be understood, but research is progressing rapidly. One form of a recently discovered gene -- HPC1 -- may cause one-third of all inherited cases of prostate cancer. Up to 10 percent of all cases of prostate cancer appear to have a genetic link. The gene appears to be especially common among African American men and may explain their high incidence rates. Researchers believe that the discovery of this gene will eventually lead to a simple blood test that could alert men of a possible increased risk.
