Prostate Health Index (phi)

An FDA approved, CE marked blood test analysis to be used as an aid in distinguishing prostate cancer from benign prostatic conditions1

phi is a proprietary calculation developed by Beckman Coulter Inc. that uses a combination of three blood tests to produce a "phi score." This phi score provides more information about what elevated PSA levels might mean and the probability of finding prostate cancer on biopsy.*

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What is phi ?

phi is three things: a simple blood test to improve early detection of prostate cancer, a tool to reduce negative biopsies and provide more confidence in your biopsy decisions, and it is used as a recommendation by the National Comprehensive Cancer Network (NCCN) Guidelines for PCa Early Detection prior to transrectal ultrasound (TRUS) guided biopsies.

phi comprises three tests in combination:

  • PSA
  • free PSA
  • p2PSA

The new p2PSA assay specifically measures [-2]proPSA. The [-2]proPSA biomarker is an isoform of free PSA that was identified as the most prostate cancer-specific form found in tumor extracts.1 The PSA, free PSA and p2PSA results are combined in the Access instrument to calculate a probability of prostate cancer.

Benefits of phi Testing

The PSA test is a widely used screening tool for prostate cancer. However, given the PSA test’s limited specificity for cancer, a more precise tool is needed for prostate cancer detection. The phi score provides better risk stratification to identify patients who need a biopsy.† The appropriate use of phi can significantly modify physicians behavior patterns and improve their ability to diagnose and manage their patients. phi is another tool to help their patients decide if a biopsy is right for them.2

The power of phi

A recent study published in Prostate Cancer and Prostatic Diseases demonstrated that physicians elected to perform fewer prostate biopsies for men who presented in the diagnostic gray zone when phi testing was included in their overall routine clinical assessment. Physicians reported that phi testing significantly impacted their patient management decision in over 73% of their cases.


Only 36% of men received biopsies when phi was included in the assessment, compared with the 60% who had to undergo such procedures before phi was available.

How is the phi analysis used in clinical practice?

Because phi analysis improves specificity for prostate cancer, it fills the diagnostic gap between PSA screening and a prostate biopsy (Figure 1).



Figure 1. Diagnostic Considerations for Prostate Cancer

What does phi score mean?

Table 1 represents clinical study data analyzed to estimate an individual patient's probability of having detectable prostate cancer based on Beckman Coulter phi results when that patient has a PSA in the diagnostic gray zone between 4 and 10 ng/mL.3 At phi cutoffs between 27 to 55, the probability of cancer ranged from 16.8 to 50.1%.‡ For example, a patient with a phi result below 27 has a 90% chance that his prostate biopsy will be negative.

Table 1. Probability of Prostate Cancer Based on phi Results Between 4 and 10 ng/mL1

phi Range* Probability of Cancer 95% Confidence Interval
0-26.9 9.8% 5.2%-15.4%
27.0-35.9 16.8% 11.3%-22.2%
36.0-54.9 33.3% 26.8%-39.9%
55.0+ 50.1% 39.8%-61.0%

Clinical study data shows phi results can be used to assess probability of cancer.

The phi diagnostic gray zone in countries outside of the U.S.and China is defined as PSA levels between 2 and 10ng/mL. The probability slightly changes based on these PSA levels (see Table 2).

Table 2. Probability of Prostate Cancer Based on phi Results Between 2 and 10 ng/mL2

(Hybritech Calibration of PSA and free PSA)
Beckman Coulter phi Range*
(Hybritech Calibration)
Probability of Cancer 95% Confidence Interval
0-21 8.4% 1.9%-16.1%
21-40 21.0% 17.3%-24.6%
40+ 44.0% 36.0%-52.9%

Clinical study data shows phi results can be used to assess probability of cancer.

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Announcement "Is it Cancer?"

Provide diagnostic clarity. Assess the probability of prostate cancer with phi.                                                                

Find out more

Journal Article Clinical Utility of the Prostate Health Index (phi) for Biopsy Decision Management in a Large Group Urology Practice

Deciding when to biopsy a man with non-suspicious DRE findings and tPSA in the 4-10 ng/ml range can be challenging, because two-thirds of such biopsies are typically found to be benign. The Prostate Health Index (phi) exhibits significantly improved diagnostic accuracy for prostate cancer detection when compared to tPSA and %fPSA1

Read article
Learn more about the superior performance of phi compared to PSA alone

Brochure The phi Clinical Summary

The superior performance of phi compared to PSA alone has been demonstrated through multiple peer-reviewed publications. Read summaries of the articles and discover the power of phi.


1Loeb S, Sanda MG, Broyles DL, et al. The prostate health index selectively identifies clinically significant prostate cancer. J Urol, 2015; 193(4):1163-9.

2Jay White B, Vittal Shenoy, et al. Clinical utility of the Prostate Health Index (phi) for biopsy decision management in a large group urology practice setting. Prostate Cancer and Prostatic Diseases. 

3Beckman Coulter Access Hybritech p2PSA Instructions for Use.

*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 2-10 ng/mL range and negative digital rectal examination DRE findings.

†Beckman Coulter, the stylized logo, and phi are trademarks or registered trademarks of Beckman Coulter, Inc

‡Biopsy outcomes of patients in the 4-10 ng/mL range.