Gene fusion test can assist in early detection of PCa, delay biopsy

August 18, 2011

When used as a supplement to an elevated PSA reading, a new urine test that detects instances of a specific genetic anomaly and the presence of the PCA3 marker can help men delay or avoid biopsy while identifying patients at the highest risk for clinically significant prostate cancer, the authors of a recently published study report.

When used as a supplement to an elevated PSA reading, a new urine test that detects instances of a specific genetic anomaly and the presence of the PCA3 marker can help men delay or avoid biopsy while identifying patients at the highest risk for clinically significant prostate cancer, the authors of a recently published study report.

The test looks for the TMPRSS2:ERG gene fusion, which occurs in about half of all prostate malignancies. The addition of PCA3 as a marker improved the performance of the test, according to the study results, which were published in Science Translational Medicine (2011; 3:94ra72).

"Testing for TMPRSS2:ERG and PCA3 significantly improves the ability to predict whether a man has prostate cancer," said lead author Scott Tomlins, MD, of the University of Michigan, Ann Arbor, who worked on the study with Arul M. Chinnaiyan, MD, PhD, and colleagues. "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."

The researchers examined urine samples from 1,312 men, all of whom had elevated PSA and had gone on to either a biopsy or prostatectomy. The samples were evaluated for TMPRSS2:ERG and PCA3, allowing for stratification of patients into low-, intermediate-, and high-score groups pertaining to cancer risk.

Biopsies showed cancer in 21% of men in the low-score group, 43% in the intermediate group, and 69% in the high-score group.

Urine test scores also correlated with tumor aggressiveness, with 7% of low-score patients having aggressive tumors versus 40% in the high-risk group.

The combined TMPRSS2:ERG and PCA3 test is not yet available clinically to screen for prostate cancer. The Michigan Center for Translational Pathology is working with Gen-Probe Inc., which has licensed the technology, and hopes to offer it to University of Michigan patients within the year, according to a press release from the university.