A man's risk of developing prostate cancer could be better measured with a urine test than with existing methods, a new study reports.

The test looks for a genetic change that occurs in some prostate cancers, and its results could be used to separate men into high-, intermediate- and low-risk groups, the researchers say.

More than 1 million men have their prostates biopsied every year in the U.S., and most of these tests are done following a prostate-specific antigen (PSA) test showing elevated levels. But the PSA test has its shortcomings — it can be elevated when cancer isn't present, and it hasn't shown a clear benefit in terms of helping men live longer, the study said.

The new urine test could be given after a man has been found to have high PSA levels, to guide the decision about whether a biopsy should be done, said the researchers, who were led by Dr. Scott Tomlins, a pathologist at the University of Michigan Medical School.

The test is based on work published in a 2005 study by the same researchers that identified a genetic change present in 50 percent of prostate cancers that were identified by a PSA screening test. That change — the fusion of two genes called TMPRSS2 and ERG — causes cells to overproduce a certain protein, and the new study shows that the genetic material involved in making that protein can be detected in urine, the study said.