Two clinical studies presented at the 2010 Genitourinary Cancer Symposium suggest that a ETS-related gene mRNA urine test (TMPRSS2-ERG or T2ERG) may be useful in diagnosing prostate cancer and predicting the results of prostate biopsies.

There are continual studies to improve the sensitivity and specificicity of serum prostate specific antigen (PSA) in diagnosing patients with prostate cancer. The current studies involve a gene called transmembrane protease, serine 2 (TMPRSS2) that codes a protein belonging to the serine protease family. This gene is up-regulated by androgenic hormones in prostate cancer cells and down-regulated in androgen-independent prostate cancer tissue.

Researchers from Walter Reed Army Medical Center have reported that a high urine score for ETS-related gene mRNA after a digital rectal examination (DRE) was associated with the diagnosis of prostate cancer on biopsy.[1] This test apparently performed well in men with PSA levels of 4 ng/mL or less.

At the 2010 Genitourinary Cancers Symposium, researchers from three U.S. and Canadian medical centers reported that the T2ERG urine test may help identify “clinically relevant prostate cancer.”[2] This study included 669 men who were referred for biopsy and/or prostatectomy. All had a urine sample collected after DRE and tested for T1ERG mRNA. Sufficient mRNA was collected on 95% of samples.

• “TMRPSS2:ERG had superior AUC (0.72) compared with sPSA (0.06) or the Prostate Cancer Prevention Trial risk calculator (0.64) for predicting prostate biopsy outcome.”
• Higher test scores were associated with “significant versus insignificant cancers on biopsy.”

The second presentation concluded: “The T2:ERG urine assay demonstrated high specificity for predicting biopsy outcome.”[3] This study included 463 men who had a prostate biopsy performed. The positive biopsy rate was 44%. The T2:ERT test had a specificity of 87% and a sensitivity of 39%. Including other risk factors—such as sPSA, %fPSA, age, prostate volume, family history, race DRE result, and prior prostate biopsy—improved prognostication. These authors suggested that diagnostic accuracy for predicting prostate biopsy outcomes could be improved by using a nomogram that combines other markers with T2:ERG.

Comments: These studies suggest that this new test might be useful in diagnosing prostate cancer. However, only further studies can tell whether or not this will be a meaningful and cost-effective test.

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