Urine Test Shows Promise in Reducing Prostate Cancer Biopsies
Pre-biopsy urine screen improves both disease detection and high-grade tumors prediction
May 7, 2012 -- In 2011, the USPSTF made a draft recommendation against PSA screening for men who are not at high-risk for prostate cancer in an effort to decrease overtreatment, despite the test’s utility in lowering mortality. This recommendation sparked instant debate and vividly highlighted the urgent need for better biomarkers for prostate cancer. Solutions to this dilemma will come in many forms, and one particularly promising biotechnological advancement has just cleared another hurdle. As highlighted in a recent article in Renal & Urology News, a recent study, led by the National Cancer Institute (NCI), has given independent validation to the use of urine screening for the presence of a molecular signature known as PCA3 to improve the detection of prostate cancer and high-grade tumors prior to invasive biopsies done either initially or for follow-up testing.
Prostate cancer cells churn out extremely high levels of genetic RNA made from the PCA3 gene and these abnormally high levels of RNA can be detected in urine. The PCA3 gene was discovered in the lab of PCF-funded researcher William B. Isaacs, PhD, by Marion Bussemakers in 1993. The California-based biotechnology company Gen-Probe—using ultra-sensitive polymerase chain reaction (PCR) assays that have, in the past, been used to improve our nation’s donor blood pool safety—commercialized the urine test and offer it now as PROGENSA PCA3. The Food and Drug Administration (FDA) approved the test in February of this year.
“The development of this test adds to our armamentarium in the fight against prostate cancer,” says Dr. Isaacs. “The PSA test, while still a very worthwhile test, is not as specific as we’d like it to be for detecting cancers that are aggressive. This [PCA3] test won’t be the end of the story, but it is an important step in the right direction,” says Isaacs.
The NCI study examined the predictive value of using PROGENSA PCA3 to detect prostate cancer. A positive PCA3 test predicted a positive biopsy of 80 percent of the time at initial biopsy; and, for men undergoing repeat biops,; a negative urine test predicted a negative biopsy 88 percent of the time.
In addition, prostate-cancer specific gene-fusion discoveries made by two other PCF-funded researchers Scott Tomlins, MD, PhD and Arul Chinnaiyan, MD, PhD, out of the University of Michigan, Ann Arbor, are currently being developed by Gen-Probe for additional urine biomarker tests for prostate cancer. In a study published last year in Science of Translational Medicine, Tomlins and Chinnaiyan and colleagues showed that using a urine test sensitive to both gene-fusion defects and RNA product of PCA3 enhanced the predictive value of PSA to find tumors on biopsy that are clinically significant—that is tumors that likely require treatment over active surveillance.
In Renal & Urology News, Dr. Robert G. Uzzo (Chairman of the Department of Surgery at Fox Chase Cancer Center) said that while not yet incorporated into most physician’s screening protocols, this new study marks a “clear, positive step toward a more risk-adjusted biopsy strategy” and a potential way forward out of the PSA testing morass.
The availability of an easy-to-use urine test that improves prostate cancer detection prior to biopsy has the potential to eliminate thousands of unnecessary prostate biopsies in the U.S. each year.