A New Right Next Step

TMPRSS2 ERG and PCA3 urine test better at detecting prostate cancer

(RxWiki News) When a man has an elevated PSA (prostate specific antigen) level, the next step is often a biopsy to see if it's cancer. That step may soon be supplemented or replaced with a urine test.

Researchers have discovered a new urine test could improve the accuracy of early prostate cancer detection, and in the process, offer men better treatment options. It could also help men delay or totally avoid a needle biopsy to diagnose the disease.

"Ask for a PCA3 test following an elevated PSA screening result."

About half of all prostate cancers have two genes that switch places and cling together. This so-called gene fusion, TMPRSS2:ERG, is believed to be the cause of the most common cancer found in men. And studies have found that when this fusion is present, cancer is too - almost always.

Still, this genetic oddity is seen only in half of prostate cancers, so researchers added the biomarker PCA 3 to the test. When both markers are present, it's much more likely that cancer has developed.

This study from the University of Michigan Comprehensive Cancer Center and the Michigan Center for Translational Pathology analyzed the urine samples of 1,312 men, each of whom had elevated PSA levels, followed either by a biopsy or surgery to remove their prostates (prostatectomy).

Researchers analyzed the urine samples for TMPRSS2:ERG and PCA3 and separated the samples into low, intermediate or high scores which indicated cancer risks. These test results were then compared to biopsy results.

Biopsies indicated cancer follows:

  • Low-score group - 21 percent
  • Intermediate group - 43 percent
  • High - 69 percent

The urine tests correlated how aggressive the cancer was based on tumor size and a measure of how abnormal the cells look (Gleason score). Researchers found that only 7 percent of low-score group had aggressive cancers while 40 percent of tumors in the high score group were aggressive.

Lead author Scott Tomlins, M.D., Ph.D., a pathology resident at the U-M Health System, says these findings suggest that the TMPRSS2:ERG and PCA3 test could become a next step, allowing men to monitor elevated PSA levels before having biopsies.

The TMPRSS2:ERG and PCA3 test is not yet available as a screening tool for prostate cancer, however PCA3 screening alone is. Researchers say the combined test should be available by late 2012.

Results from this study are published in Science Translational Medicine.

Review Date: 
August 4, 2011