An investigational urine test may help men with an elevated prostate-specific antigen (PSA) level decide whether a prostate biopsy is necessary. These results were published in Science Translational Medicine.
Men 50 years of age or older in the United States are often offered a PSA blood test for the early detection of prostate cancer. The test may be offered at a younger age to men at high risk of prostate cancer. PSA levels tend to be elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate. Men with an elevated PSA level may undergo a prostate biopsy in order to determine whether prostate cancer is present.
Because PSA is not a perfect predictor of prostate cancer, researchers have continued to search for ways to improve prostate cancer screening. If other tests are better able to predict who does and does not have prostate cancer, it would, among other things, reduce the number of unnecessary prostate biopsies.
Researchers from the University of Michigan recently reported on an investigational urine test that detects a genetic change (TMPRSS2:ERG gene fusion) that is present in roughly half of all prostate cancers. Because the genetic change is not found in all prostate cancers, the researchers also tested for another marker of prostate cancer known as PCA3.
The ability of these two markers to predict the presence of prostate cancer was evaluated among 1,312 men with elevated PSA levels. Based on the urine test results, the men were classified as being at low, intermediate, or high risk of having prostate cancer. These results were then compared with biopsy results.
- The results of the urine test provided information about the likelihood of prostate cancer: Prostate cancer was found in 21% of the men classified as low risk, 43% of the men classified as intermediate risk, and 69% of the men classified as high risk.
- The urine test also helped to identify more aggressive prostate cancer. Aggressive prostate cancer (defined on the basis of tumor size and Gleason score) was identified in 7% of the low-risk men and 40% of the high-risk men.
These results suggest that it may be possible to use the urine test to help guide biopsy decisions among men with elevated PSA. Men who have elevated PSA but a low risk of prostate cancer based on urine testing may be able to avoid or delay prostate biopsy. The combined TMPRSS2:ERG and PCA3 test is not yet available, but researchers continue to work on its development.
Reference: Tomlins SA, Aubin SMJ, Siddiqui J et al. Urine TMPRSS2:ERG fusion transcript stratifies prostate cancer risk in men with elevated serum PSA. Science Translational Medicine. August 3, 2011. Vol. 3, Issue 94, p. 94ra72.