Assessing the patient’s probability of having detectable prostate cancer when total
prostate specific antigen (PSA) concentrations are between 4–10 ng/mL.
Results from a prospective, multicenter clinical trial found that phi provides better risk stratification and reduces unnecessary biopsies by 30%, which reduces medical costs and time for the patient.1
Several PSA isoforms have been identified that can further increase the specificity of PSA for prostate cancer. In particular, the [-2] form of proPSA (p2PSA) shows improved performance over either total or free PSA for prostate cancer detection on biopsy. The prostate health index (phi) is a formula that combines all 3 PSA forms (total PSA, free PSA, and p2PSA) into a single score. Phi is calculated using the following formula: (p2PSA/free PSA) x square root (PSA).
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% clinical sensitivity, the clinical specificity of phi was 16.0%, compared to 8.4% for free PSA and 6.5% for PSA.
Prostatic biopsy is required for diagnosis of cancer.
Patient Preparation: Specimens for testing should be drawn prior to prostate manipulations such as digital rectal examination (DRE), prostatic massage, transrectal ultrasound (TRUS), and prostatic biopsy.
Collection Container/Tube: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Spin down within 3 hours of draw and separate serum from cells.
Day(s) and Time(s) Test Performed
Monday through Friday; 6 a.m.-12 a.m.
Saturday; 6:30 a.m.-5 p.m.
1. Loeb S, Martin S, Broyles, D, et al. The Prostate Health Index (phi) Selectively Identifies Clinically Significant Prostate Cancer. J. Urology, Jan. 2015.
Mayo Clinic Laboratories
This post was authored by the Marketing Team at Mayo Clinic Laboratories.