First of all, what is PSA? PSA is a term that stands for prostate-specific antigen. PSAs are proteins that are created in the prostate tissue and are enzymes that free the sperm from the semen after ejaculation. These PSAs can be used to screen for prostate cancer.
The History of PSAs
The FDA approved PSA testing to monitor the progress of prostate cancer that was already diagnosed in the mid-80s. Then, in the mid-90s, the FDA approved the use of PSA as a means of prostate cancer screening along with a digital rectal examination.
Who should get PSA tests? And how often?
It was once recommended that men over 50 should get PSA tests performed annually. It was also recommended that men with a familial history of prostate cancer and men of African American descent should get PSA tests performed annually after the age of 40. It has also been recommended that men who are receiving testosterone replacement therapy should actively get PSA tests. However, after assessing the harm of early prostate cancer screening, most recommendations are now done based on an individual basis with many considerations.
The presence of PSAs can be based on numerous conditions such as:
- Size of the prostate gland
- Age of the individual
- Presence of inflammation in the prostate
- Presence of prostate cancer
- Presence of a urinary tract infection
- Influence of medication such as testosterone, finasteride, dutasteride
- Recent prostate examination
- Indirect pressure on the perineum such as from riding a bike
- Recent sexual activity
Free PSA testing
Another test that is often done is a free PSA test, which measures the amount of PSA protein that is not bound to protein. This test is usually done when the total PSA is between 4 and 10 ng/ml. This test can help evaluate the presence of prostate cancer. When the ratio of free PSA relative to the total PSA is less than 25%, the greater the presence of prostate cancer.
Other Common PSA Testing techniques
There are many other techniques used to screen for prostate cancer by evaluating the PSAs within the body, such as:
- Age-specific PSA – Comparing the PSA relative to the individual age
- PSA Density – Total PSA level divided by the volume of transition zone measurement of the prostate
- PSA velocity – Monitoring the elevation of PSA velocity over time
There have also been newer forms of biomarker tests to help evaluate the indication of a prostate biopsy, such as:
- PCA3 – evaluate the level of a specific RNA strand in a urine sample after a vigorous prostate massage.
- Four-Kallikrein Panel (4Kscore) – compares the ratio total, free, and intact PSA as well as the presence of human kallikrein-2 (hK2) to determine the risk of detecting an aggressive form of prostate cancer.
- Prostate Health Index (PHI) – applies a sophisticated algorithm that measures the presence of total and free PSA as well as proPSA (a precursor form of free PSA) from a blood sample.
If you are interested in learning more about PSAs or screening for prostate cancer, you should seek out a board-certified urologist.