What is the significance of family studies in prostate cancer?

Prostate cancer is the most frequently diagnosed malignancy in American men, occurring in as many as 15% of men in the United States. Interestingly, the incidence of prostate cancer in African American men is 50% higher than in age matched Caucasian American controls.

In general, African American men have the highest incidence of prostate cancer of any ethnic subgroup of the world's population. The causes of this disparity are not yet well understood. Studies examining the disproportionately higher incidence and death rate of this cancer among African Americans indicate that this dire impact might be caused by an earlier onset of the disease, delayed diagnosis, and other compromising behaviors.

Although the majority of cases of prostate cancer are sporadic, a number of possible explanations for this increased incidence are being actively explored including dietary, hormonal, and genetic factors. It is well known that the familial component is a strong risk factor for prostate cancer with an increased relative risk occurring in relatives of affected men.

Men with a first degree relative with prostate cancer have a 2-3 fold increase in risk relative to the general population. It means that a brother, father or son of a prostate cancer case has a risk of prostate cancer which approximately double the population risk.

Relatives with a stronger family history would be more likely to have prostate cancer over relatives of a single case, which means the more cases in a family, the higher would be the risk to other male relatives, e.g., while men with a single case of prostate cancer in the family have an approximately two-fold increased risk of prostate cancer, males with two first-degree relatives with prostate cancer have five-fold increased risk. Therefore, the familial aggregation of prostate cancer is useful in studying the inherited risk to the disease. In addition, relatives of early onset cases would have a higher risk of having prostate cancer over that of later onset cases.

The genetic studies performed to date on mostly Caucasian families suggest that multiple genes are involved in hereditary prostate cancer (i.e., genetic risk factors may differ among the families). So far, there are not enough data collected on African American families to determine whether these suggested genes, reported in Caucasian families, are also important for African American families.

Prostate cancer in African American men may caused by a different set of genes than in Caucasian Americans. Alternatively, the same genes may be important in both populations, but with a higher frequency of the disease-causing form of the gene in the African American population.

The participation of African Americans in the genetic studies of prostate cancer will help to resolve some of the issues concerning the high occurrence of prostate cancer in this ethnic group. Also, the detection of existing genetic loci or new genetic loci in conjunction with modern prostate cancer screening procedures will improve the detection and diagnosis of this cancer at an earlier age when the cancer is curable.

So, the information found from the genetic family study will help to reduce the mortality of prostate cancer in African Americans. In the long run, men can be identified as having the specific risk factor or not which in turn will help with cancer prevention strategies.