A study published in Prostate Cancer and Prostatic Diseases demonstrated that physicians elected to perform fewer biopsies when phi testing was included in their overall, routine, clinical assessment. Phi testing is recommended for men presenting with elevated serum total prostate-specific antigen (PSA) in the 4-10 ng/mL range and a non-suspicious digital rectal exam (DRE). These men are often referred to as being in a ‘diagnostic grey zone’, since typically less than 35% of such men who are biopsied are found to be positive for prostate cancer.
This potentially exposes the remaining two-thirds of such men to unnecessary complications associated with biopsies such as bleeding, pain and the risk of infection. The findings, published in the October online issue of the journal, were based on a comparison of over 500 men tested with phi to a historical control group of similar men who were seen by the same participating urologists within the previous 24 months, and prior to the commercial implementation of phi testing in their practice.
Prostate cancer is the third-leading cause of cancer death in men, with one in seven receiving a diagnosis during his lifetime. In 2017, approximately 161,360 new cases of prostate cancer were identified, with 60 percent of those occurring in men 65 years of age or older. Common methods for detecting prostate cancer include DRE and the serum PSA, followed by biopsy and transrectal ultrasound for final diagnosis. In recent years, however, the use of PSA screening for prostate cancer has come under scrutiny, with concerns that an increasing number of false-positives were leading to unnecessary invasive procedures. In fact, in May 2012, the U.S. Preventative Services Task Force, an independent volunteer panel of national experts in prevention and evidence-based medicine, recommended against PSA-based screening for prostate cancer in all men, while calling for a better test and better treatment options.
According to the study titled, “Clinical Utility of the Prostate Health Index (phi) for Biopsy Decision Management in a Large Group Urology Practice Setting,” men receiving a phi test showed nearly a 24% reduction in biopsy procedures performed compared to the historical control group (36.4% versus 60.3%, respectively, p<0.0001). Furthermore, physicians reported that the phi score significantly impacted their patient management plan in over 73% of cases, including biopsy deferrals when the phi score was low, and decisions to perform biopsies when the phi score indicated an intermediate or high probability of prostate cancer (phi≥36). The study investigators concluded that phi testing provides valuable information that can significantly modify physician behavior patterns and improve their ability to diagnose and manage their patients. This additional information assists physicians in making more informed decisions about patient care, and helps to reduce the number of prostate biopsies performed as a result of over-diagnosis. By reducing the number of unnecessary specialized procedures, physicians are able to provide better care to patients by minimizing both the emotional and physical burden that can be associated with unnecessary invasive procedures.
“Effective biomarkers share three optimal characteristics,” said Jay White, Ph.D., MPH, director of laboratory services at Carolina Urology Partners, PLLC. “First, they have to demonstrate high-specificity to differentiate between cancer and normal cells, and, also to isolate prostate cancer from other cancers and diseases. They also need to have high-sensitivity to identify the disease early and in all individuals in whom it is present. Lastly, they need to be easily detected with non-invasive methods. Biomarkers with poor specificity may lead to false positive results, leading to unnecessary testing that exposes individuals to complications associated with biopsies, such as bleeding, pain and the risk of infection, and creating an economic burden for the patient and healthcare provider, alike.”
The FDA-approved phi test is exclusive to Beckman Coulter, and helps distinguish prostate cancer from benign conditions,1 using a score calculated from a combination of three blood tests. The “phi score” provides additional information as to what elevated PSA levels might mean and the probability of finding prostate cancer on biopsy. The phi results are intended to be used as an aid in distinguishing prostate cancer from benign prostatic conditions in men 50 years of age and older with total PSA results in the 4-10 ng/mL range and negative DRE findings. When combined with the patients’ clinical risk factors and family history, the phi score can help determine individualized patient management protocols.
“The phi test provides more information about the probability that a patient may have prostate cancer, giving both the patient and doctor additional insight to guide a decision as to whether a prostate biopsy is needed,” said Michael Samoszuk, M.D., chief medical officer, Beckman Coulter Diagnostics.