Looking at whether a man’s uncles and great-grandparents, among other second- and third-degree relatives, had prostate cancer could be as important as looking at whether his father had prostate cancer. A more complete family history would give physicians a new tool to decide whether or not a prostate-specific antigen (PSA) test was appropriate, according to this new study published in Prostate (2014; doi:10.1002/pros.22925).

“Family history is a substantial risk factor for prostate cancer,” said Lisa Cannon-Albright, PhD, University of Utah professor of genetic epidemiology and an investigator at the Huntsman Cancer Institute (HCI) in Salt Lake City. “But typically, a clinician will ask a patient whether there are any people in the family with prostate cancer, possibly identifying whether they are first-degree relatives. And that’s about as far as it goes.”

Cannon-Albright’s team used data from the Utah Population Database, which correlates genealogic and medical information for more than 7.3 million people, to create individualized risk estimates for men based on prostate cancer history in their first-, second-, and third-degree relatives.

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They calculated individualized relative risks for men with prostate cancer family histories, based on the number, degree, and age at diagnosis of their affected relatives for many different constellations, or combinations of these factors.

To condense their findings for clinical use, the team identified constellations that conferred greater than two-fold and three-fold risk. Patients and clinicians can refer to this data to help them determine an appropriate individual plan for prostate cancer screening.

According to the study, two-thirds of men in Utah have some increased risk of developing prostate cancer based on their family history of the disease, but only a minority have substantially increased risk, since 10% have three times the risk, and 26% have double the risk, compared with men from families with no history of prostate cancer.

Because this population is genetically similar to most white men of Caucasian and northern European descent, the findings can be extrapolated to these populations as well.

“The clinical application of our findings is especially relevant because there is no consensus on prostate cancer screening,” said co-author Robert A. Stephenson, MD, professor of urologic oncology at the University of Utah and an HCI investigator. “Knowing prostate cancer risk estimates associated with a man’s detailed family history can help pinpoint the men who will benefit from targeted screening.”

The team found that even though the advent of the PSA screening test increased the overall number of prostate cancer diagnoses, the proportion of cases with associated family history remained the same before and after PSA screening became widely used. Also, the study showed family history of prostate cancer among a man’s maternal relatives contributes to elevated risk equally with history among paternal relatives.