Image: The IsoPSA is a new blood test for the accurate prediction of overall risk of malignant prostate cancer (Photo courtesy of the Cleveland Clinic).
A new blood test for determination of prostate cancer risk was found to be more accurate than the current gold standard PSA (prostate specific antigen) test.
Prostate-specific antigen, the current gold standard in prostate cancer detection, is distinct from virtually all other cancer biomarkers because of its almost exclusive specificity to the prostate, allowing direct assessment of physiological conditions in the gland with a simple blood test. Unfortunately, PSA is tissue- but not cancer-specific, and over diagnosis and overtreatment of PSA-detected, biologically insignificant cancers are widely recognized as key limitations in its clinical utility.
The IsoPSA test was developed to evaluate structural changes in the PSA isoforms that correlate with prostate cancer. This approach not only reduces the number of false positives, it also allows providers a window into the cancer grade before deciding on whether a biopsy is indicated.
In a recent study, investigators at the Cleveland Clinic (OH, USA) conducted prospective validation of the clinical performance of IsoPSA, a novel structure-focused protein biomarker, to assess potential discrimination of high-grade prostate cancer (Gleason≥7) from benign or low-grade disease (Gleason=6).
They found that more than 40% of biopsies could have been avoided in both the preliminary study (45.1%) and validation study (47%), suggesting that use of IsoPSA may substantially reduce the need for biopsy, and may thus lower the likelihood of over detection and overtreatment of nonlethal prostate cancer.
"To be clinically useful, a biomarker must be both tissue-specific and cancer-specific. While PSA is prostate-specific, it is not specific for prostate cancer, leading to diagnostic inaccuracy and too many unneeded biopsies," said first author Dr. Eric Klein, chairman of the Glickman Urological & Kidney Institute at the Cleveland Clinic. "IsoPSA fulfills both the tissue- and cancer-specificity needed for a useful biomarker, and this validation study shows that it can more accurately detect high-grade cancer and reduce the rate of unneeded biopsies in patients at low risk of this disease."
The validation study was presented May 18, 2018, at the San Francisco, CA, USA, 13th Annual Meeting of the American Urological Association and was published in the April 2018 online edition of the Journal of Urology.