A urine test might one day be able to tell which prostate cancer patients need immediate treatment and which don't, British researchers report.
"Prostate cancer can be divided into low and high risk -- the low-risk men rarely require treatment, and the high-risk certainly do," said study author Jeremy Clark, a senior research associate at Norwich Medical School at the University of East Anglia in Norfolk. "However, there is a third group, called intermediate risk, which falls between these extremes, and the treatment pathway for these men is less clear."
Prostate cancer is common -- over 40% of 50-year-old men will have prostate cancer -- but not everyone is dying of it, so deciding which men to treat is not always easy, Clark said.
"We have developed a simple urine test that can measure the presence of aggressive cancer and also how much aggressive cancer is present," he said.
"The test appears to be able to assess how much aggressive cancer is present in these intermediate-risk men, and so could be used to identify a group of intermediate-risk men that could avoid immediate treatment, which includes surgery and radiotherapy, and instead, these men could be monitored by active surveillance by being retested yearly to see if their disease is stable or not," Clark said. "Around a quarter of the intermediate-risk men could fall into this group."
Avoiding treatment is important, as treatment can often have unwanted side effects, he explained. "Surgical removal of the prostate can commonly lead to impotence and loss of urinary control, something you don't want if you don't have to," Clark said.
A previous version of the test, called the Prostate Urine Risk (PUR), could only tell whether men had high- and low-risk cancers. With fine tuning, however, the test may now be able to diagnose men with intermediate-risk disease who may only need watchful waiting.
To date, the only tests available to gauge the aggressiveness of prostate cancer include blood tests, rectal exams, MRI scans or biopsies.
Specifically, the urine test can help doctors know the patient's Gleason score, which determines the type of prostate cancer. A Gleason score of 6 is low-grade, 7 is intermediate-grade, and 8 to 10 is high-grade cancer.
The urine test not only measures aggressive cancer, but also increasing amounts of aggressive cancer in the prostate, Clark said. So it can show which men at intermediate risk may require treatment and which may not, he said.
The test will also help monitor disease in men who do not need treatment and identify the expansion of aggressive disease, Clark said. It can assess the Gleason pattern for intermediate-risk cancer without the need for a biopsy, he added.
For the study, Clark and his colleagues looked at biopsies and other tests of more than 270 men with various stages of prostate cancer, as well as samples of prostates that have been removed, comparing urine tests with the patients' diagnosis.
Dr. Anthony D'Amico, a professor of radiation oncology at Harvard Medical School in Boston, said the test is promising but not yet ready for use with patients.
"This is the kind of thing we're looking for," he said. "Something that, with a high degree of accuracy, can say you got a Gleason pattern that needs treatment, or you don't have it so you can continue on surveillance or you need to come off surveillance. That's what we want."
According to D'Amico, however, the test still misses men who need treatment and identifies men who didn't need treatment but whose prostate was removed.
"I think, right now, it's premature to know how good the test really is," he said. "It's interesting, but not quite ready for prime time.
"If you're looking at this for a population of 100,000 people, it will benefit most, but there'll be some errors where you'll miss some people with high-grade disease or you'll overcall others," D'Amico said.
"I think that's the caution, and this comes down to economics, so if you say I'd be willing to use this test, because, say, 80% of the time it finds Gleason grade 4 and 20% it misses it, and that's good enough, this might be a very good test to use, but it's where you draw the line," he said.
The report was published Nov. 3 in the journal Life.
For more on prostate cancer, see the American Cancer Society.
SOURCES: Jeremy Clark, PhD, senior research associate, Norwich Medical School, University of East Anglia, Norfolk, U.K.; Anthony D'Amico, MD, PhD, professor, radiation oncology, Harvard Medical School, Boston; Life, Nov. 3, 2021