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Multiplexed Urine Test Predicts Prostate Cancer Risk in Men with Elevated PSAs

Posted Aug 12 2011 12:00am

This is follow-up to a note that I posted February 4, 2008, about a multiplexed urine test for prostate cancer (see: First Generation Multiplexed Urine Test for Prostate Cancer ). More than three years later comes news of progress concerning such a urine screening test. The test will provide information about the clinical aggressiveness of a possible cancer of the prostate in men with elevated PSAs (see: Urine Test Predicts Prostate Cancer Risk; Test could reduce unnecessary needle biopsies ). Below is an excerpt from the article:

A new screening test makes use of urine, rather than blood, to identify the men most at risk of prostate cancer, and may even provide information about how aggressive a tumor is likely to be. The standard screening test for prostate cancer is a blood test for a protein called prostate specific antigen (PSA). But PSA is also produced by non-cancerous conditions such as enlarged prostates or infection, so is not very specific....[Arul] Chinnaiyan and his colleagues have developed a new test that detects two markers specific to prostate cancer. One, called TMPRSS2:ERG, is the fusion of two genes, TMPRSS2 and ERG, and is found in around half of prostate tumors found through PSA screening. The other, a non-coding RNA called PCA3, is a very sensitive marker, found in unusually high levels in more than 95% of prostate cancers. The researchers studied 1,065 men [with],,,elevated PSA. They used their test to stratify the men into low-, intermediate- and high-score groups. Biopsies confirmed cancer in 21% of the low-score group, 43% of the intermediate group and 69% of the high group....Futher studies will allow refinement of the test, but the researchers say patients in the high risk group should definitely get a biopsy. High-scoring men with a negative biopsy might also choose to be closely monitored given their high risk. Higher urine test scores also correlated with the aggressiveness of the cancer, as determined by the size of the tumor and a standard metric of cell abnormality called the Gleason score. This is something that biopsies cannot do reliably. The results pave the way for Gen-Probe ...to seek approval from the US Food and Drug Administration (FDA)....But urine-based tests are not likely to replace the PSA test any time soon. "We are initiating long-term, prospective trials to begin gathering enough data to determine whether this test could, one day, serve as a replacement," says Chinnaiyan. "But the bar will be pretty high when attempting to replace a test physicians have used for so long."

This is all good news -- the very real possibility of a multiplexed urine test that can provide useful prognostic information for men with an elevated serum PSA. Dr. Chinnaiyan makes a very important point about the PSA in the article above, which is that it has been in use for so long that it's not about to be replaced by another test despite its imperfections (see: One-Time PSA before Age 50 Can Stratify Risk for Subsequent Prostate Cancer ; Solid Advice for Older Men Regarding PSA Screening for Prostate Cancer ; At What Age Should Routine PSA Screening Be Terminated? ). There is so much accumulated knowledge and clinical experience with PSA that the best approach is to fill in the blank spots with information that PSA can't provide. One note of caution, however. The FDA has been somewhat ambivalent about multiplexed testing in the past. Many of my previous notes have referred to such tests as IVDMIAs . Hopefully, this new urine test will prove as beneficial as these new data suggest.

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