The risk of prostate cancer increases with the number of family members with the disease, particularly brothers, and with younger age at diagnosis, a nationwide study has shown.

The national Swedish family cancer database was used to estimate age-specific familial risks of being diagnosed with prostate cancer according to the number and type of affected first-degree relatives and according to paternal and fraternal age at diagnosis. The registry includes records of >11.8 million individuals and their cancers over nearly 50 years.

The authors also calculated the risk of dying from prostate cancer according to family history. This is the largest family study published with more than 26,000 prostate cancer cases, of which 5,600 were familial.

Age-specific hazard ratios (HRs) were calculated for diagnosis and death from prostate cancer. HR of prostate cancer diagnosis increased with the number of affected relatives and decreased with increasing age. The highest HR was for men under the age of 65 with three affected brothers (HR 23); the lowest for men aged

65-74 with an affected father (HR 1.8). Overall, HRs were higher for men with affected brothers than with an affected father. This trend was also seen in men with multiple affected family members. When the number of affected family members was the same, the risk was higher when only brothers were diagnosed compared with when father and brothers were diagnosed. In families with several affected members, the HRs were highest for those patients whose youngest relative was diagnosed before the age of 60.

Given the high prevalence of prostate cancer in the community, many patients present to their GP with a family history of the disease. The question often asked of their GP is how much does this history increase their personal risk of prostate cancer, and what degree of screening they should undergo as a result. This can be very difficult to answer.

This study has produced multiple HRs for different numbers of affected relatives and according to age at diagnosis. The take home message, however, is that the risk of prostate cancer increases with the number of affected first-degree family members, particularly brothers, and with younger age at diagnosis. Therefore, patients who fall into higher-risk groups can be identified.

The man with two brothers diagnosed under the age of 60 would be well advised to have regular PSA testing from early on, with a low threshold for urological referral. While the man with a father diagnosed with prostate cancer in his late eighties can be reassured that this does not have a great impact on his personal risk of prostate cancer.

 

Dr Jonathan Rees

 

• Brandt A, Bermejo JL, Sundquist J et al. Age-specific risk of incident prostate cancer and risk of death from prostate cancer defined by the number of affected family members. Eur Urol 2010. doi: 10.1016/j.eururo.2010.02.002