SAN FRANCISCO—A new urine test based on a highly specific gene-fusion biomarker may accurately predict the presence of clinically significant prostate cancers at biopsy and radical prostatectomy, according to findings presented here at the Genitourinary Cancers Symposium.

The assay measures TMPRSS2:ERG (T2:ERG), which is found in approximately 50% of prostate tumors. Its presence is associated with increased tumor cell growth, increased ability to invade and metastasize, and decreased apoptosis.

Sheila M. Aubin, PhD, of Gen-Probe Inc., San Diego, and collaborators tested urine specimens obtained from 669 men after they underwent digital rectal examinations. The specimens yielded sufficient mRNA for T2:ERG analysis in 635 of 669 patients (94.9%). John T. Wei, MD, MS, Professor of Urology at the University of Michigan in Ann Arbor, who presented study findings, said the assay has a specificity of 85% at a score above 100 and 95% at a score above 200 for predicting clinically significant prostate cancer at biopsy.

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For these same scores, respectively, the specificities were 95% and 100% for predicting clinically significant prostate cancer at radical prostatectomy.

In 101 men undergoing prostatectomy, higher T2:ERG scores were associated with upgrading at prostatectomy (from biopsy Gleason score 6 to prostatectomy Gleason score 7), higher prostatectomy Gleason scores (above 6), and large tumor volume, but not prostate weight.

“This T2:ERG test and others like it that have an ability to differentiate clinically significant cancers from the latent ones will move us into a new era of prostate cancer diagnostics where the goal is not merely to find cancers but to find potentially harmful cancers,” Dr. Wei said.