Researchers at Wake Forest University School of Medicine have found that a simple blood test can determine which men are likely to develop prostate cancer.
Previous studies have already found five genetic variants associated with prostate cancer risk. Although each variant alone is moderately associated with the risk for prostate cancer, this new study found that when the variants are assessed together, they have a strong cumulative effect.
In the study, the researchers found that a man with four of the five variants has a 400 to 500 per cent increased risk of developing the disease as compared to men with none of the variants.
When a family history of prostate cancer is added to the equation, for a total of six risk factors, a man with at least five of the six factors has an increased risk of more than 900 per cent.
The findings are based on an analysis of DNA samples from 2,893 Swedish men with prostate cancer and 1,781 healthy men of similar ages; all were participants in a prostate cancer study in Sweden.
The researchers found that each variant was independently associated with prostate cancer risk and that the variants are fairly common in the population.
But together, these five variants and a family history accounted for almost half (46 percent) of the prostate cancer patients.
"This is significant and could affect clinical care. The information could substantially improve physicians' ability to assess risk and determine the need for more aggressive screening or even a biopsy," said senior researcher Jianfeng Xu, M.D., Dr. PH., professor of epidemiology and cancer biology.
He said that the test might be especially useful in men with a family history of prostate cancer or those who have a marginally elevated PSA (prostate specific antigen).
"Our finding provides an opportunity to supplement the well-established risk factors by looking at how many of these variants a man has inherited. It may provide a much better weapon to guide clinicians," Xu said.
This study was the first to evaluate whether there is a cumulative effect from having multiple variants.
"When we considered the variants together we discovered their potential for predicting individual risk. Because of the cumulative effects of these risk variants and family history, for the first time associations found through genome-wide screening appear to be useful in clinical practice," Xu said.
The researchers said further study is needed to determine how genetic testing may complement PSA testing.
The study is published in New England Journal of Medicine.