Prostate Health Index (phi)

An FDA approved, CE marked blood test to be used as an aid in distinguishing prostate cancer from benign prostatic conditions1
The Prostate Health Index (phi) is a calculation that uses a combination of three blood tests to produce a “phi score.” This score
provides more information about what elevated PSA levels might mean and the probability of finding prostate cancer on biopsy.*

What is the Prostate Health Index (phi)?

The Prostate Health Index 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;
  • is used as a recommendation by the National Comprehensive Cancer Network (NCCN) Guidelines for PCa Early Detection prior to transrectal ultrasound (TRUS) guided biopsies.

The Prostate Health Index (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 the Prostate Health Index (phi)

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 physicians and help their patients decide if a biopsy is right for them.2

The power of Prostate Health Index (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 testing was included in the assessment, compared with the 60% who had to undergo such procedures before phi was available.2

More than 80 published clinical papers and meeting abstracts demonstrate the health benefits and economic value of phi.

How is the Prostate Health Index (phi) used in clinical practice?

Because phi 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
The Prostate Health Index fills the diagnostic gap between PSA screening and a prostate biopsy.

How to Interpret the Prostate Health Index Results to Guide Treatment

Table 1 represents clinical study data analyzed to estimate an individual patient’s probability of having detectable prostate cancer based on phi results when that patient has a PSA in the diagnostic gray zone between 4 and 10 ng/ml.3 At phi cut-offs 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. 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)
phi Range*> 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.

phi® Patient Selection Criteria

Men may be a candidate for the Prostate Health Index Test if you are:

  • age 50 years and older with an elevated PSA between 4ng/ml and 10ng/ml.
  • or any men with total PSA values as low as 2 ng/ml. (supported by Peer reviewed published studies)

Frequently asked questions

Q: Is phi (p2PSA) FDA approved?

A: Yes, phi (p2PSA) received FDA approval in June 2012.

Q: Is phi in the National Comprehensive Cancer Network (NCCN) Guidelines?
A: Yes, phi was first added to the NCCN Guidelines in 2014.

Q: Are there any clinical studies on phi available?
A: Yes, there are more than 80 published studies on phi from around the world. Summaries of these clinical studies can be found under the Science Section.

Q: Do you have to run PSA and fPSA assays to calculate phi?
A: Yes, phi is calculated using the test results from PSA, fPSA and p2PSA, all using the same method of calibration.

Q: Is phi positioned as a first-line repeat/confirm PSA or as a reflex after PSA is confirmed and in the 4–10 ng/ml range?
A: phi labeling indicates it should be run after confirmation that PSA is in the 4–10 ng/ml range. This indication extends to both initial and repeat biopsies.

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. https://doi.org/10.1038/s41391-017-0008-7.

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 4–10 ng/mL range and negative digital rectal examination DRE findings.

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

Indicated for use as an aid in distinguishing prostate cancer from benign prostatic conditions in men aged 50 years and older with total PSA results in the range of 4–10 ng/ml in the U.S. (2–10 ng/mL outside the U.S.)

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