New Diagnostic Tool May Improve Accuracy of PSA Screening

A new prostate cancer screening test yielded more detailed and specific results for prostate-specific antigen (PSA) levels than currently available tests, according to a large, multicenter study that raises hopes for advances in the widely used but highly controversial diagnostic tool.

William Catalona, MD, whose landmark research helped establish the PSA test in the early 1990s, will report results in the May issue of The Journal of Urology from a study of the new Pro-PSA test and a prostate health index that the researchers developed.

Catalona is director of the clinical prostate cancer program at the Robert H. Lurie Comprehensive Cancer Center and a professor of urology at the Feinberg School of Medicine at Northwestern University, Chicago, Illinois. The university said the test already is approved for sale in Europe.

The study, conducted at 10 sites, involved 892 men with no history of prostate cancer, a normal rectal exam, ≥6-core biopsy, and PSA levels of 2 to 10 ng/ml, which clinicians consider a difficult-to-diagnose range. Although death rates from cancer in the United States have declined since the advent of widespread PSA screening, there are fears that screening leads to overdiagnosis and unnecessary treatment.

“This new test is more specific and accurate than the currently available blood tests for early prostate cancer detection,” Catalona said in a press release Friday. “This will focus on the detection of more life-threatening prostate cancers and reduce unnecessary biopsies in men 50 years of age and older.”

Additionally, the index that researchers developed measured the lower-range PSA levels at 80% to 95% sensitivity, detecting specificity and area under the curve levels that exceed existing PSA tests, the research team said.

The Pro-PSA test measures a subtype of free PSA called [-2]pro-PSA; the index consists of a mathematical formula that takes total PSA into account.

“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 [it is that] the patient has aggressive prostate cancer,” Catalona said.

Catalona gathered research support from the National Cancer Institute, the Urological Research Foundation, and Beckman Coulter, Inc, a biomedical test company based in Brea, California, that markets PSA tests.