A new PSA test to screen for prostate cancer (PCa) is more accurate than commercially available tests at identifying men with the disease, particularly the aggressive form of the cancer, data show.

The only currently available FDA-approved screening tests for PCa result in a high number of false positives and lead to unnecessary biopsies and possible over-detection and over-treatment of indolent cancer. The new test, called Pro-PSA, measures a more specific PSA subform called -2 Pro-PSA.

The test is even more accurate when its results are analyzed with a mathematical formula that provides an overall Prostate Health Index. The formula divides the Pro-PSA number by the free-PSA. Then the quotient of the two is multiplied by the square root of the total PSA. 

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“The logic behind the formula is that the higher the Pro-PSA and total PSA and the lower the free-PSA, the more likely the patient has aggressive prostate cancer,” said lead investigator William Catalona, MD, Director of the Clinical Prostate Cancer program at Northwestern University in Chicago.

Dr. Catalona was the first to show, in 1991, that a simple blood test measuring PSA levels could be used to detect PCa.  In this current study, he and his colleagues followed 892 patients from 10 sites. The results, which was scheduled to be published in the May issue of the Journal of Urology, showed the new screening test was particularly useful for patients with a normal prostate exam whose PSA was in the 2-10 ng/mL range. 

In their study, the researchers found that an increasing Prostate Health Index was associated with a 4.7-fold increased risk of prostate cancer and a 1.16-fold increased risk of Gleason 7 or greater disease on biopsy. Index results were not associated with age and prostate volume, Dr. Catalona said. 

The new Pro-PSA test was recently approved for commercial use in Europe. The FDA is currently reviewing the data from this current study.