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.
By combining the new urine test with a test for prostate specific antigen 3, the researchers could tell if a man has prostate cancer better than they can with only a PSA test, the study said.
The researchers screened more than 1,000 men with the new test and based on the results, separated them into low-, intermediate-, and high-risk groups. Subsequent biopsies resulted in a cancer diagnosis in 21 percent, 43 percent and 69 percent of men in these groups, respectively.
The study was limited in that 85 percent of the participants were Caucasian, so additional studies will need to determine whether the findings extend across all ethnicities, the researchers said. And because the men in the study had already had completed PSA testing, other work will need to examine the usefulness of the urine test in men who have not undergone PSA tests.
The study was published today (Aug. 3) in the journal Science Translational Medicine.
Pass it on: A urine test could determine a man's risk of developing prostate cancer.