New PSA test more accurate, reduces false positives

A new PSA test appears to more accurately identify men with prostate cancer, particularly the aggressive form of the disease, and substantially reduce false positives compared with the two currently available tests, say researchers from Northwestern University, Chicago.

The study, which was published in the Journal of Urology (2011; 185:1650-5), followed 900 patients from 10 sites, including Northwestern. The results showed that the new test, called Pro-PSA, is particularly useful for patients with a normal prostate exam whose PSA is 2.0 ng/mL to 10 ng/mL.

"This new test is more specific and accurate than the currently available blood tests for early prostate cancer detection," said lead investigator William Catalona, MD. "This will focus on the detection of more life-threatening prostate cancers and reduce unnecessary biopsies in men 50 years of age and older."

The Pro-PSA test measures a more specific PSA subform called (–2) Pro-PSA. Researchers say the test becomes 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.)

"The logic behind the formula is that the higher the Pro-PSA and the total PSA and the lower the free PSA, the more likely the patient has aggressive prostate cancer," Dr. Catalona said.

Dr. Catalona said Pro-PSA was recently approved for commercial use in Europe, and that the FDA is reviewing his team’s research.

Dr. Catalona is a paid consultant for Beckman Coulter, Inc., which collaborated with Dr. Catalona’s team on the study.