From the Guidelines
A normal PSA level with a %free PSA of 9% warrants further evaluation due to increased risk of prostate cancer, and I recommend a urological consultation for consideration of prostate biopsy. While the total PSA may be within normal range (typically under 4 ng/mL), the percentage of free PSA is concerning, as values below 10% are associated with a higher likelihood of malignancy 1. The %free PSA test measures the ratio of unbound PSA to total PSA in the blood, with lower percentages suggesting a higher probability of cancer rather than benign conditions like BPH.
During your urologist visit, additional risk stratification tools may be employed, such as:
- Prostate MRI
- PSA density calculation
- Newer biomarkers like the 4K score or PHI (Prostate Health Index) Age, family history, and other risk factors will also influence the decision-making process. Some key points to consider include:
- The level of PSA correlates with the risk of prostate cancer, with approximately 15% of men with a PSA level of ≤4.0 ng/mL and a normal DRE having prostate cancer diagnosed on end-of-study biopsies 1
- Biomarkers that improve the specificity of detection, such as percent free PSA, 4Kscore, or phi, may be informative in patients who have never undergone biopsy or after a negative biopsy 1 Regular monitoring with repeat PSA testing in 3-6 months would be appropriate if biopsy is deferred. This situation requires clinical judgment as the combination of normal total PSA with low %free PSA represents a diagnostic challenge requiring specialized evaluation.
From the FDA Drug Label
The ratio of free to total PSA (percent free PSA) remains constant even under the influence of finasteride tablets. If clinicians elect to use percent free PSA as an aid in the detection of prostate cancer in men undergoing finasteride therapy, no adjustment to its value appears necessary. With a normal PSA and a %free PSA of 9, the fact that the percent free PSA remains constant under the influence of finasteride tablets 2 suggests that this %free PSA value can be used as an aid in the detection of prostate cancer without needing any adjustments.
- A %free PSA of 9 is generally considered to be in the lower range, which may indicate a higher risk of prostate cancer.
- However, no conclusion can be drawn about the presence or absence of prostate cancer based solely on this information.
- Further evaluation and monitoring are necessary to determine the presence of prostate cancer.
From the Research
Normal PSA with %free PSA of 9
- A %free PSA of 9 is considered low, which may indicate a higher risk of prostate cancer 3, 4.
- Studies have shown that a lower %free PSA is associated with a higher risk of prostate cancer, particularly in men with a total PSA between 2 and 25 micrograms/l 3.
- In one study, a %free PSA of less than 27% was found to be useful for detecting early-stage but clinically significant cancers in men with a total PSA value between 2 and 4 ng/mL and normal digital rectal examination (DRE) findings 4.
- However, it's essential to consider other factors, such as digital rectal examination (DRE) results and total PSA levels, when evaluating the risk of prostate cancer 5, 6.
- Digital rectal examination (DRE) can cause a modest increase in total and %free PSA, while prostate needle biopsy can cause more dramatic increases in both forms of PSA 7.
- The %free PSA can return to baseline levels within 24 hours after biopsy, which could affect the use of measurements of the %free PSA in clinical practice 7.