Prostate cancer incidence among distant relatives on both sides of a man’s family can help predict whether he will develop the disease, suggests a new study published in the journal Prostate

"Family history is a substantial risk factor for prostate cancer," study author Lisa Cannon-Albright, genetic epidemiology professor at the University of Utah, said in a news release. "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 and her team examined genealogic and medical information of 7.3 million individuals— mostly of Caucasian and northern European descent— and assessed their prostate cancer risk based on first-, second- and third-degree relatives. Researchers analyzed the frequency, degree and age of diagnoses of the men’s affected relatives, and determined a “constellation,” or a combination of these factors, to confer measurements for two-fold and three-fold risk groups for the study participants.

Study authors observed that two-thirds of Utah men have some increased risk of developing prostate cancer due to family history. About 10 percent have three times the risk, and 26 percent have double the risk, compared to men who didn’t have a family history of the disease.  

Researchers noted that family history was just as effective at predicting disease incidence as the prostate-specific antigen (PSA) test, a screening method widely used among physicians. While the screening test increased the number of diagnoses, the proportion of cases associated with family history remained the same before and after the advent of the PSA test.

When assessing a man’s prostate cancer risk, history of the disease among a man’s maternal relatives is just as big of a predictor as the incidence among his paternal relatives, researchers noted.

"There may be a synergistic effect if a man has both maternal and paternal family history," Cannon-Albright said in the news release. "We want to investigate this further, along with bringing other factors such as race, socioeconomic status, and previous diagnosis with another type of cancer into the risk calculations. This will broaden the populations to which the risk estimates apply."

Study author Robert A. Stephenson, a urologic oncology professor at the University of Utah, said the findings are important because physicians haven’t reached a consensus on prostate cancer screening.

“Knowing prostate cancer risk estimates associated with a man’s detailed family history can help pinpoint the men who will benefit from targeted screening,” he said in the news release.

Next, the team plans to study how family history may play a role in breast and lung cancer prediction, the news release noted.