Michigan researchers develop highly specific urine test for prostate cancer
A new urine test is now available that can help doctors more about a man’s prostate cancer, which could lead to better decisions about treatment.
The good news comes from the Prostate Cancer Foundation who says though they are not endorsing the test, the combination of the urine test and PSA results could mean a more personalized approach to prostate cancer diagnosis and treatment that could help avoid biopsy for tens of thousands of men.
The PSA test has been under scrutiny for several reasons. One is that it isn't always reliable. Another reason is that it can't specify whether prostate cancer is aggressive enough to need treatment or if the prostate gland is inflamed or infected, which also causes elevations in the antigen manufactured by the gland.
The urine test - Mi-Prostate Score (MiPS) - makes PSA testing more useful to doctors because it gives a bigger picture.
The Prostate Cancer Foundation explains 44 percent of biopsies fail to find cancer even when PSA level rises to 4.1 ng/ml in the blood - which is the threshold for recommending biopsy.
Biopsy risks recently highlighted
Additionally, biopsies carry some risks including bleeding, infection and difficulty urinating after the procedure. In a 2013 trial, called the PLCO (Prostate, Lung, Colorectal, and Ovarian) screening trial, mortality rate after biopsy was found to be 1.3 per 1000 at 120 days for men who did not have prostate cancer and 3.5 per 1000 men who did have the disease.
The findings of the study were discussed in a Medscape release June, 2013 by Dr. Gerald Chodak who said the impact of biopsies cannot be ignored when weighing the risks and benefits that Chodak called "somewhat disturbing".
Additionally, treating prostate cancer that is non-lethal with surgery or radiation can cause erectile dysfunction, impotence and urinary incontinence.
How the test works
The test uses a combination of two scores for prostate cancer – one based on PSA levels in the blood and the other from RNA markers that are specific for prostate cancer.
Additionally, one marker measured with the urine test is a piece of RNA made from a gene called PCA3 that is overactive in 95 percent of all prostate cancers and is only expressed in prostate tissue.
The second marker is RNA that is made only when two genes (TMPRSS2 and ERG) abnormally fuse. The presence of this fusion RNA in a man’s urine is highly specific for prostate cancer.
Urine testing for PCA3 was approved by the FDA in 2012 for men whose initial biopsy was negative but uncertain if a second biopsy is needed. The new urine test for prostate cancer is more sensitive.
Findings published in the journal Science Translational Medicine found men with TMPRSS2:ERG and PCA3 in their urine had the highest rates of prostate cancer.
Drs. Scott Tomlins and Arul Chinnaiyan of the University of Michigan discovered the T2:ERG gene fusion abnormality.
Tomlin said in a press release: “This combination test is not designed to say definitively whether you have aggressive prostate cancer at diagnosis,” says Tomlins. Yet, the test, he says, can provide men with a more accurate estimate of the likelihood that they do in fact have cancer, and the likelihood that they have an aggressive cancer.”
For more information or to send a urine specimen for testing, you or your doctor can call MLabs at 800-862-7284 or www.mlabs.umich.edu.
Image credit: Wikimedia Commons