What is Percent-Free PSA?

Prostate cancer effects millions of men each year, whether newly diagnosed or living with prostate cancer. Despite the amount of lives this cancer affects, the tools for diagnosis fall short.  For this reason it is important to use the tools that we do have to their fullest capacity.  The percent free PSA, for instance.

Currently, the two most widespread only methods available for prostate cancer screening are the PSA test and digital rectal exam. Although, each of these exams are not very sensitive in detecting prostate cancer, they are reed flags which allow doctors to better identify those at risk for prostate cancer.  The lack of sensitivity of these tests, is why the practice of individualized medicine rather than reflexive medicine is so important.


Percent Free PSA

While the actual PSA result is not always critical to prostate cancer detection, the trend and velocity at which PSA changes are critical to detection.  The same goes for the percent free PSA value, which can give doctors more information about the likelihood of cancer than with just the PSA alone.

This PSA related test is an important resource for doctors when trying to get more information from a non-specific diagnostic test. What exactly is the percent free PSA, and how can it give us better diagnostic power?  PSA, prostate specific antigen, circulates in the blood in two forms. In one form, the antoge is attached to certain blood proteins and in the other for the prostate antigen is unattached or free.  This unattached PSA is what we are looking at. A low ratio of free PSA to total PSA, that means anything under < 25% shows an increased risk, and may be more indicative of prostate cancer. 

Free PSA is more often used for men with elevated PSA values, in order to determine those men who are most at risk for a prostate cancer diagnosis. Men with BPH typically have higher free PSA whereas cancer typically causes the production of attached PSA.  A percent-free PSA between 10% and 25% is considered an intermediate range, while below 10% is considered low.

Critics of the PSA test say its widespread use has resulted in too many unnecessary screenings and treatments causing undue anxiety, and side effects of treatments like impotence and incontinence.  But it is important to note that ever since the PSA test was introduced as a screening tool for prostate cancer in 1986, doctors have had the ability to diagnose cancer earlier, at a more treatable stage.  Before the PSA test, prostate cancer was most often diagnosed at more advanced, less treatable stages. 

The free PSA can help men who have borderline PSA’s especially, determine whether they should be having follow up biopsies.  Of course, a low percent free PSA, even when it is found in conjunction with a high regular PSA level is not a diagnosis for cancer.  A biopsy is needed to make that determination.  So although the PSA test is not perfect, using PSA related tests like the percent free PSA test can give us more information and help doctors give patients more individualized and overall better care.