IsoPSA Test Could Reduce Overdiagnosis, Overtreatment in Prostate Cancer

A new blood-based diagnostic test (IsoPSA) for prostate cancer that evaluates structural changes in prostate-specific antigen (PSA), instead of measuring the blood levels of the protein, could reduce unnecessary biopsies and identify the right patients that need treatment.

The research, published in European Urology, was conducted in 5 academic and community urology centers in the United States. The study sample was heparin-plasma, collected from 261 men scheduled for a prostate biopsy between August 2015 and December 2016, following a suspicious digital rectal exam or rising PSA levels.

“Despite criticism, PSA has transformed the landscape of early detection, screening, and management of prostate cancer in the last few decades,” said Eric Klein, MD, chair of Cleveland Clinic’s Glickman Urological & Kidney Institute, to Science Daily. “Unfortunately, PSA is tissue-specific but not cancer-specific, leading to overdiagnosis and overtreatment of biologically insignificant cancers, which is widely recognized as a key limitation in its clinical utility.”

The advantage of this study was that patients were their own control, because the researcher could compare the IsoPSA test against the PSA test in the same patient.

The results showed a 53.3% prevalence of prostate cancer in the study cohort, with a 33.7% prevalence of high-grade prostate cancer. Importantly, there was no significant correlation between IsoPSA and serum PSA levels, and IsoPSA outperformed the PSA test for both endpoints that were measured. For a cutoff selected to recommend biopsy, IsoPSA demonstrated a 48% reduction in false-positive biopsies, and for a cutoff selected to identity men at low risk of high-grade disease, there was a 45% reduction in the false-positive rate.

Another study author, Mark Stovsky, MD, also at the Cleveland Clinic Glickman Urological & Kidney Institute, expressed hope that IsoPSA, requiring only a blood draw, would have good clinical utility once validated.