FDA Approves Test to Aid Post-PSA Biopsy Decisions
The Access Hybritech p2PSA test is approved for use in men aged 50 or older who have a PSA test score between 4 and 10 ng/ml but who show no signs of cancer during a digital rectal exam.
A PSA test score between 4 and 10 ng/mL often prompts physicians to recommend a prostate biopsy. Most biopsies from men with PSA scores in that range, however, reveal no cancer or identify cancers that likely will never pose a health risk. And biopsies themselves have risks, including the risk of life-threatening infection.
The Access Hybritech p2PSA test measures a form of PSA called [-2]proPSA in the blood. Results from the test are combined with a PSA score and a measurement of free PSA to calculate the Prostate Health Index, or phi.
FDA approval was based on a clinical study of nearly 660 men, approximately half of whom had prostate cancer. In the study, the phi score was better able to distinguish between benign conditions and prostate cancer than the PSA score. The study also found that the probability of having prostate cancer detected following a biopsy rose as the phi score increased.
But the study was not designed to determine whether the phi test reduces the risk of dying of prostate cancer, noted Dr. Barry Kramer, director of NCI’s Division of Cancer Prevention.
Several earlier studies of the phi test, including a study sponsored by NCI’s Early Detection Research Network, have suggested that higher phi scores also may indicate more aggressive prostate cancer.
However, there is no standard phi score that indicates whether a biopsy should be performed, the FDA noted. “The choice of an appropriate…phi score to be used in guiding clinical decision-making may vary for each patient and may depend in part on other clinically important factors or on family history of disease,” the agency explained in its approval summary.
The Access Hybritech p2PSA will be available for sale in the United States later this year, according to Beckman Coulter, the company that developed the test.