ORLANDO – With questions and controversy swirling concerning the efficacy of the widely used prostate-specific antigen (PSA) test, Beckman Coulter's (Fullerton, California) Clinical Diagnostics division (Brea, California) is studying the feasibility of developing a new blood test to detect benign prostatic hyperplasia (BPH), the non-cancerous form of prostate enlargement.
Early published findings on such a new test – which Beckman said would be the first of its kind – were presented during last week's joint conference of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC; Milan, Italy) and the American Association for Clinical Chemistry (AACC; Washington) at the Orange County Convention Center.
"PSA isn't what it was in the late 1980s," and it isn't "doing what it used to do," Bernard Cook, PhD, manager of scientific and professional relations for immunodiagnostics at Beckman Coulter, told Diagnostics & Imaging Week.
Cook's comments point to the test's lack of reliability, stemming from the fact that PSA readings often are picking up what turns out to be BPH or some other problem, though it is still useful at detecting more aggressive prostate cancers.
According to Beckman, four out of five men will eventually develop BPH, an enlargement of the prostate gland that occurs later in life. It is non-cancerous but troublesome because it constricts the urethra, causing problems with urination.
The new laboratory test – which would be called BPH-A – is under development for use on Beckman Coulter's Access family of immunoassay systems. The test detects an isoform of PSA, which exists in abnormally high levels in the blood of men who have an enlarged prostate, the company said.
According to the research presented at the conference, BPH-A "appears to be more specific to BPH than more traditional disease markers," Cook said in a company statement.
Expanding on the point, he used the analogy of armed police for dealing with petty violations. "You wouldn't send out a force of armed police trained in catching bank robbers if all they were catching was traffic violators. While it's likely that occasionally a bank robber might be caught, it is not an efficient use of their time. And so [also] with the PSA test. Unfortunately, men who are thought to possibly have prostate cancer are often subjected to biopsies, and the stress of not knowing if they actually have cancer, with the current PSA test."
Beckman Coulter is developing a research-use-only (RUO) version of BPH-A that will be used by select researchers to further the usefulness of the test. Cook told MDD that to keep the project "on a timeline," feasibility studies are scheduled to be completed by the end of this year. If all goes well, a product could be ready for market in 2006, Cook said.
In addition to Cook, other authors on the IFCC/AACC study are William Catalona, MD, a urologist and professor of the department of urology at Northwestern University's Feinberg School of Medicine (Chicago) and Beckman Coulter scientists Stephen Mikolajczyk and Charles Weinzierl.
In September 2004, Dr. Thomas Stamey, professor of urology at Stanford University (Palo Alto, California), published an article in the Journal of Urology saying that the "era of PSA is over." Ironically, Stamey authored a study the 1987 study in The New England Journal of Medicine promoting increased blood PSA levels as the same as digital rectal examination for detecting prostate cancer.
In the more recent article, he said, "Serum PSA was related to prostate cancer 20 years ago. In the last five years, PSA has only been related to benign prostatic hyperplasia."
Still, Cook said that while the incidence of prostate cancer is increasing like many cancers, the "death rate due to prostate cancer is decreasing."
Beckman Coulter's presentation at the IFCC/AACC conference also highlighted published research on another new blood test called proPSA.
According to the study, the proPSA test, also under development, may show greater specificity for prostate cancer than the PSA test. The company said that the study "also suggests" that elevated levels of proPSA may be associated with more aggressive forms of prostate cancer.
Cook told D&IW that if the BPH-A test does not prove itself in feasibility studies, the company then would focus its attention on the proPSA test going forward.
He said Roche Diagnostics (Indianapolis) already has a similar test, called free PSA.
Beckman Coulter also offered what it called "an early look" at its UniCel DxC 600i clinical system, which combines chemistry and immunoassay systems on one workstation. It is pending submission to the FDA. The company also introduced the Vidiera NsD Nucleic Sample Detection Platform for the "fully automated detection of nucleic acids, post amplification."