A urine test could soon help doctors detect prostate cancer early and better evaluate a patient”s treatment options, according to a new study involving an Indian-origin scientist.
Prostate cancer screening is currently based on a blood test to detect prostate-specific antigen (PSA). But that test often produces false results and leads to unnecessary biopsies.
The new test developed by the University of Michigan Comprehensive Cancer Center and the Michigan Center for Translational Pathology appears to be better at detecting prostate cancer, and could help some men delay or avoid a needle biopsy while pointing out men at highest risk for clinically significant prostate cancer.
The test looks for a genetic anomaly that occurs in about half of all prostate cancers, an instance of two genes changing places and fusing together.
This gene fusion, TMPRSS2:ERG, is believed to cause prostate cancer.
Studies in prostate tissues show that the gene fusion almost always indicates cancer. But because the gene fusion is present only half the time, the researchers also included another marker, PCA3. The combination was more predictive of cancer than either marker alone.
“Testing for TMPRSS2:ERG and PCA3 significantly improves the ability to predict whether a man has prostate cancer,” said lead author Scott Tomlins, M.D., Ph.D., a pathology resident at the U-M Health System.
“We think this is going to be a tool to help men with elevated PSA decide if they need a biopsy or if they can delay having a biopsy and follow their PSA and urine TMPRSS2:ERG and PCA3,” he added.
The researchers looked at urine samples from 1,312 men at three academic medical centers and seven community-based hospitals. The men all had elevated PSA levels and had gone on to receive either a biopsy or prostatectomy, surgery to remove their prostates.
The researchers evaluated the urine samples for TMPRSS2:ERG and PCA3 and stratified patients into low, intermediate and high scores, indicating their risk of cancer. They then compared this to biopsy results.
Biopsies indicated cancer in 21 percent of men from the low-score group, 43 percent in the intermediate group and 69 percent in the high group.
Further, the urine test scores correlated with how aggressive the cancer was.
“Many more men have elevated PSA than actually have cancer but it can be difficult to determine this without biopsy. This test will help in this regard. The hope is that this test could be an intermediate step before getting a biopsy,” said senior study author Arul Chinnaiyan, M.D., Ph.D., director of the Michigan Center for Translational Pathology and S.P. Hicks Professor of Pathology at the U-M Medical School.