Patients with non-suspicious digital rectal exam findings and total PSA in the 4.0- to 10.0-ng/mL range are far less likely to be biopsied if they’ve had Prostate Health Index (phi) testing than if they don’t, according to a new study.
“Inclusion of the phi test provides more information about the probability that a patient may have prostate cancer, further informing the decision on whether a prostate biopsy is needed,” said lead study author Jay White, PhD, MPH, of Carolina Urology Partners, Huntersville, NC. “In recent years, there has been an indictment of PSA screening, most notably from the U.S. Preventive Services Task Force. With this study of the clinical utility of phi, which includes PSA as well as free PSA and [–2] proPSA, we can clearly see an improvement in clinical decision-making and patient management with respect to screening for prostate cancer.”
This is the first multicenter study, reflecting results from four large urology practices around the U.S., to analyze phi testing’s impact in real-world practice. The findings were published online in Prostate Cancer and Prostatic Diseases (Nov. 20, 2017).
The authors used a test shown to improve diagnostic accuracy, the FDA-approved phi, which combines three immunoassays—total PSA, free PSA, and [–2] proPSA—into a single numerical phi score.
Researchers conducting the pivotal trial for FDA approval found the phi test resulted in nearly a threefold prostate cancer detection improvement, compared to total PSA alone. A later meta-analysis of nearly 3,000 patients suggested a pooled clinical specificity of 31.6% at the 90% sensitivity threshold, according to the study.
For the current study, the authors compared urologists’ management of a prospective group of 506 men, ages 50 years and older, with total serum PSA between 4.0 ng/mL and 10.0 ng/mL and nonsuspicious digital rectal exam findings who had phi testing, to a like cohort of 683 men who didn’t receive phi testing.
They found 36.4% of men in the phi group were biopsied compared to 60.3% of those in the non-phi cohort. While phi testing scores influenced biopsy deferrals, as well as decisions to perform biopsies, all in all, use of the testing resulted in a net 24% reduction in biopsies, according to the study.
“It was remarkable to see the rate of biopsy drop so significantly without changing the rate of prostate cancer detection. In other words, there was a significant reduction in the rate of unnecessary biopsy procedures as a result of better informed patient selection,” Dr. White said.
phi scores influenced urologists’ patient management plans in 73% of cases, after consideration of other clinical factors, according to the study. And 92% of the urologists’ responses suggested the phi score was a helpful communication tool with patients and a potential anxiety-reducer when scores were low.
Careful identification of patients is very important, according to Dr. White.
“The test performs very well in men 50 years of age and older with total PSA between 4.0 and 10.0 ng/mL concomitant with negative digital rectal exam findings,” he said. “As with any laboratory result, it cannot be acted upon in isolation and must be considered along with the patient’s clinical risk factors and family history to determine how best to manage the patient.”
This study doesn’t include randomization and longitudinal follow-up, which should be addressed in future studies, according to the authors.
“I think it is the tip of the iceberg with respect to improving the screening of men for prostate cancer, while controlling costs to the patient and the health care system at large. I'm very excited about gathering longitudinal follow-up data so that we can analyze long-term outcomes in men tested with phi,” Dr. White said.
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