Washington, Jan 17 : Scientists have taken a step forward in revealing the causes of prostate cancer, by finding that a combination of five gene variants raises the risk of the disease dramatically.
A study of more than 4,000 Swedish men found that a strong family history of prostate cancer together with the presence of all five markers considerably increased the risk of developing the disease.
The genetic markers were present in nearly half the men who were later diagnosed with prostate cancer.
The international research team, comprising of researchers from Johns Hopkins Brady Urological Institute, Wake Forest University and the Karolinska Institute in Sweden, plans to sample DNA from U.S. populations of men to determine if these genetic changes prevail outside of Sweden.
The team at Wake Forest University in North Carolina and Johns Hopkins University in Maryland drew blood from 2,893 prostate cancer patients and 1,781 men without the disease in Sweden.
They found 16 small changes in the genetic code that were more common to men with prostate cancer than those without the disease. Then they created a test using the most common of these changes, called single nucleotide polymorphisms or SNPs (pronounced "snips).
Men with four or more of these SNPs were nearly 4.5 times more likely to be in the prostate cancer group, they reported.
"Our finding provides an opportunity to supplement the well-established risk factors by looking at how many of these variants a man has inherited," Wake Forest's Dr. Jianfeng Xu said in a statement.
"It may provide a much better weapon to guide clinicians," Xu added.
"This work strongly suggests that because of the combination of polymorphisms we inherit, one man may be more on the path to developing prostate cancer than another," says William B. Isaacs, Ph.D., of the Johns Hopkins Brady Urological Institute, who participated in the study.
The Prostate-Specific Antigen test, which is the current test for prostate cancer, is unreliable and can give misleading results.
Scientists now hope to test men from other countries to establish whether the genetic markers are present in the wider population.
The markers, however, do not suggest which men are at risk of an aggressive cancer or a more slow growing form of the disease.
"This information is not yet available as a genetic test for risk of prostate cancer, but efforts are under way to rapidly develop one," Isaacs said.
"While these findings need to be validated and refined, it's a step in the right direction to revealing the genetic-based reasons for this cancer that we have been looking for over the past 15 years," he added.
Results are published online in the Jan. 16 edition of the New England Journal of Medicine.