Urine test shows promise for prostate cancer detection

[kkmalaysia]

A prototype urine test has been shown to be highly specific for detecting prostate cancer and could even help to reduce the number of unnecessary biopsies, US researchers suggest.
 
Moreover the results showed some correlation to disease severity markers, suggesting that the test could be used to distinguish between mild and aggressive forms of cancer.
 
The urine test detects the presence of a fusion between the TMPRSS2 (T2) and ERG genes, which is found in around 50 percent of prostate cancers.
 
“Many cancers detected at biopsy are low volume, low grade. There is a real need for tests that can help determine which of those men should receive aggressive treatment such as prostatectomy, and which could potentially be monitored more conservatively,” said lead researcher Dr. Jack Groskopf, who presented the results at the recent Genitourinary Cancers Symposium in Orlando, US.
 
“The key next steps here are to follow up and confirm the results that we have generated to date and, perhaps more importantly, to start looking at the correlation between the urine test and pathologic features in prostatectomy tissues, such as tumor volume stage and grade,” he said.
 
Commenting on the results, Dr. Howard Sandler, chair of radiation oncology at Cedars-Sinai Medical Center, Los Angeles, said: “The fact that this gene fusion is related to the progression and development of prostate cancer in half of all men who develop prostate cancer has major implications for diagnosis [and] hopefully, for therapy as well. This unique fusion protein might become a therapeutic target at some point in the future.”
 
In a preliminary study of 556 men due to undergo prostate biopsy the urine test was 84 percent specific, reported Groskopf, a senior research scientist at Gen-Probe Incorporated, the San Diego-based company which is developing the test. For serum prostate-specific antigen (PSA) testing this figure is just 27 percent, he said, adding that the other current screening method – digital rectal exam – is also hampered by its low specificity.
 
“As a result the majority of prostate biopsies are negative, and you could argue that we are doing too many biopsies,” he said.
 
The sensitivity of the urine test was 42 percent – a favorable result considering that with only half of cancers containing the T2:ERG gene fusion, the theoretical maximum would be 50 percent, Groskopf added.
 
The urine test showed significant correlations to aggressiveness indicators such as the Gleason Score, the percentage positive prostate cores and the Epstein criteria.
 
Researchers from the University of Michigan, who are collaborating with Gen-Probe on the test, recently published another research paper linking sarcosine, a glycine derivative, to more aggressive forms of prostate cancer. This metabolite and its pathways could not only serve as a disease severity marker but also as a target for therapeutic intervention in future, they suggest.
[Nature 2009 Feb 12;457:910-4]