August 1, 2017
The prostate health index or phi test reduces the need for prostate cancer biopsies by 30 percent.
ROCHESTER, Minnesota — Mayo Clinic, working collaboratively with Beckman Coulter, now offers a prostate cancer-screening assay called the prostate health index (or phi) test that may help physicians distinguish prostate cancer from benign prostate conditions. Results from a prospective, multicenter clinical trial found that the blood-based test, which was developed by Beckman Coulter, reduces unnecessary biopsies by 30 percent.
The phi is a mathematical formula that provides the probability of prostate cancer on biopsy by combining three tests (prostate-specific antigen [PSA], free PSA, and p2PSA) into a single score. The score is tailored to each patient, aiding in the diagnosis of prostate cancer. Essentially, the test fills the diagnostic gap between a prostate blood screening and prostate biopsy.
“The phi score can help guide clinical decision-making,” says Alicia Algeciras-Schimnich, Ph.D., a clinical chemist and chair of the Division of Clinical Biochemistry and Immunology at Mayo Clinic. “Health care providers and their patients will receive more accurate information about the meaning of an elevated PSA level and the probability of finding prostate cancer on a biopsy.”
The test is available to Mayo Clinic patients and to health care providers worldwide through Mayo Medical Laboratories (MML). MML is the reference laboratory of Mayo Clinic, offering advanced laboratory testing and pathology services to more than 4,000 health care organizations in more than 70 countries. MML collaborated with Beckman Coulter, a leader in life sciences and diagnostic instrumentation, to be able to offer the test.
“Beckman Coulter’s test is FDA-approved and recommended in the guidelines from the National Comprehensive Cancer Network for PCa early detection,” says Michael Samoszuk, M.D., chief medical officer, Beckman Coulter Diagnostics. “The phi score provides guidance to help decide whether or not to biopsy the prostate in men whose total PSA falls within a diagnostic gray zone.”
Adds Dr. Algeciras-Schimnich, “Prostate cancer biopsies add heightened anxiety for patients. There are increased medical costs and the possibility of biopsy complications. By using the phi test, health care providers can reduce negative biopsies by 30 percent, which is significant.”
About the phi Test (Test ID: PHI11)
The phi test is a simple, multi-analyte blood test that may help physicians distinguish prostate cancer from benign prostatic conditions in men age 50 years or older with total PSA results in the 4 to 10 ng/mL range, helping them make more informed biopsy decisions. The FDA-approved test may help to reduce the number of biopsies that are negative for prostate cancer.
In a multicenter study that compared the performance of PSA, free PSA, p2PSA, and phi in men undergoing prostate biopsy due to a serum PSA concentration between 4 and 10 ng/mL, phi was the best predictor of any prostate cancer, high-grade cancer, and clinically significant cancer. At 95 percent clinical sensitivity, the clinical specificity of phi was 16.0 percent, compared to 8.4 percent for free PSA and 6.5 percent for PSA. The phi score may be used to determine the probability of prostate cancer on biopsy in men with total PSA in the 4 to 10 ng/mL range. Low phi scores are associated with a lower probability of finding prostate cancer on biopsy, and higher phi scores are associated with an increased probability of finding prostate cancer on biopsy. The choice of an appropriate phi score cutoff to be used in guiding clinical decision-making may vary for each patient and may depend on other clinical factors or on family history of disease.
Study reference: Catalona WI, Partin AW, Sanda MG, et al: A multicenter study of pro-prostate specific antigen combined with prostate specific antigen and free prostate specific antigen for prostate cancer detection in the 2.0 to 10.0 ng/ml prostate specific antigen range. J Urol 2011 May; 185(5):1650-1655.
Dr. Algeciras-Schimnich has received consulting income within the past 12 months from Beckman Coulter.
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The Mayo Clinic Department of Laboratory Medicine and Pathology and its reference laboratory Mayo Medical Laboratories provide advanced laboratory testing and pathology services to support 4,000 health care organizations around the world. Revenue from this testing is used to support medical education and research at Mayo Clinic, a nonprofit worldwide leader in medical care, research, and education for people from all walks of life. Complemented by collaborations with diagnostic and biotechnology companies, the department maintains a robust diagnostic test-development program, launching more than 150 new tests each year.
Beckman Coulter Diagnostics helps health care and laboratory professionals provide better patient care by delivering the accurate diagnostic information they need, when they need it. For more than 80 years, Beckman Coulter has been the partner of choice for health care organizations. Our scalable instruments, comprehensive diagnostic tests, and business management services are trusted by hospitals, laboratories, and other critical care settings around the world. We share in our customers’ mission toward continuous improvement and quality patient care because we believe when efficiency and clinical outcomes are improved, patients benefit, and we can move health care forward for every person.