Familial Risk of Aggressive Prostate Cancer Quantified

Swedish researchers say their findings are more useful for counseling men with a family history of prostate cancer.
Swedish researchers say their findings are more useful for counseling men with a family history of prostate cancer.

Swedish researchers have provided new estimates of the hereditary risk of significant prostate cancers (PCa) that may aid in patient counseling. 

Clinicians have long known that having a father or brother with PCa doubles a man's risk for the disease, but many of these cancers would turn out to be indolent. So Ola Bratt, MD, PhD, of Lund University, Par Stattin, MD, PhD, of Umea University, and colleagues used Prostate Cancer data Base Sweden, a compilation of population-based registries that captures a vast majority of PCa cases in the country, to estimate the risks of significant PCa requiring treatment. The investigators calculated risks of any PCa, non-low risk PCa, and high-risk PCa for 51 897 brothers of 32 807 men with PCa. The probabilities are in essence absolute risks, they noted. Non-low risk disease was defined as Gleason score 7 or above, prostate-specific antigen (PSA) level 10 ng/mL or above, T3–4, N1, and/or M1. High-risk PCa comprised cases that were Gleason score 8 and above, T3–4, PSA level above 20 ng/mL and above, N1, and/or M1.

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The probability of any prostate cancer was 4.8% at age 65 years and 12.9% at age 75 years, according to results published online in the Journal of the National Cancer Institute. The chances of non-low-risk PCa were lower: 2.8% at age 65 years and 8.9% at age 75 years. For high-risk PCa, the odds were 1.4% at age 65 years and 5.2% at age 75 years.

If a man had a brother with PCa, the probabilities of any PCa at age 75 were 30.3%, non-low-risk PCa, 18.8%, and high-risk PCa, 8.9%. At age 65, those risks were 14.9%, 7.3%, and 3.0%, respectively.

Risk increased when a man had more than 1 sibling with PCa. Men with 2 affected brothers had a 55.1%, 33.2%, and 13.6% probability of any PCa, non-low-risk PCa, and high-risk PCa at age 75, respectively.

"Clearly, the probabilities of non-low-risk and, in particular, high-risk cancer are highly relevant when counseling men with familial prostate cancer," the investigators wrote. “We suggest that these probabilities are included in future clinical guidelines."

The investigators said they were surprised to find that any PCa can confer substantial hereditary risks regardless of its severity. "We expected that the risk of aggressive prostate cancer would not be much increased in brothers of men with the indolent form, but it turned out to [be] almost as high as the risk among men with aggressive prostate cancer in the family," Dr Bratt said in a press release. He urged clinicians to share this risk information with patients.

Sources

1. Bratt O, Drevin L, Akre O, Garmo H and Stattin P. Family History and Probability of Prostate Cancer, Differentiated by Risk Category - a Nationwide Population-Based Study. J Natl Cancer Inst 108(10): djw110. 2016 July 11. doi: 10.1093/jnci/djw110. [Epub ahead of print]

2. New findings concerning hereditary prostate cancer. Lund University. 11 Jul 2016 [press release].

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