1847 [-2]PROPSA IN COMBINATION WITH PSA AND FREE-PSA, USING THE BECKMAN COULTER ACCESS IMMUNOASSAY SYSTEMS IMPROVES PROSTATE CANCER DETECTION RELATIVE TO PSA AND FREE PSA. A MULTI-CENTER PROSPECTIVE CLINICAL STUDY

Article Outline

• INTRODUCTION AND OBJECTIVES
• METHODS
• RESULTS
• CONCLUSIONS
• Copyright

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INTRODUCTION AND OBJECTIVES 

The limited clinical specificity of PSA and %fPSA has been a long-term issue when using these markers for prostate cancer (PCa) detection. This study was aimed at evaluating the use of [-2]proPSA, a fPSA isoform, in a multi-center, prospective clinical trial.

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METHODS 

892 subjects (430 PCa and 462 benign by biopsy) with PSA from 2-10 ng/mL were enrolled from 7 clinical centers. Subjects were > 50 years of age, with non-suspicious DRE. 97% of subjects were prospectively collected and 98% had > 10 core biopsies. [-2]proPSA, PSA and fPSA were analyzed on the Beckman Coulter Access 2 Immunoassay Analyzer. We compared the utility of PSA, %fPSA and a formula combining PSA, fPSA, and [-2]proPSA (Beckman Coulter Prostate Health Index or phi***) to assess PCa risk.

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RESULTS 

phi significantly improved the clinical specificity relative to %fPSA for PCa detection. At 95% sensitivity the specificity of phi was about 2-fold higher than %fPSA. ROC analyses (Figure) for PSA, fPSA, [-2]proPSA, %fPSA, and phi resulted in areas under the curve (AUC) of 0.525, 0.615, 0.557, 0.648, and 0.703, respectively (all with p < 0.003 relative to chance alone except PSA with p = 0.199). A significant relationship was found between phi and the relative risk of PCa in individual men, with higher phi values indicating higher risk of PCa (Table). The probability of PCa ranged from 11% for phi values < 25 to 52% for phi values ≥ 55.

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CONCLUSIONS 

The use of phi significantly increased the specificity compared to %fPSA for PCa detection in men with PSA levels of 2-10 ng/mL and non-suspicious DRE. A strong relationship between phi and probability of PCa was also demonstrated. We conclude that phi may add significant information regarding individual patient risk and may be used as an aid in patient management.

**Not intended as off-label promotion of any BCI product. ***Pending FDA approval.