The concept of prostate specific antigen (PSA) density is just one of many recent advances in more fully understanding the relationship between prostate cancer and PSA.
The Basics of PSA Density
PSA is produced by prostate cells -- whether they are normal or cancerous. Men who have larger prostates, logically, have more prostate cells and, in general, produce more PSA regardless of whether they have cancer or not.
To correct for this, the prostate’s volume is measured via transrectal prostate ultrasound. The PSA level is then divided by the size of the prostate to calculate the PSA density.
A high PSA density means that a relatively small volume of prostate tissue is making a lot of PSA; a low PSA density means that a large volume of prostate tissue is making relatively little PSA.
Does Your PSA Density Actually Matter?
Yes and no.
There is evidence that a high PSA density indicates a higher risk of prostate cancer.
There is not, however, quite as good evidence that this likely higher risk of prostate cancer really changes the proper diagnosis or treatment for those found to have a high PSA density. Not all experts agree that PSA density should change the way that a physician diagnoses, monitors, or treats prostate cancer. Some doctors feel that PSA density is simply not helpful to them when making decisions and choose to ignore it.
Overall, men found to have a high PSA density likely should be more vigilantly monitored for prostate cancer, and their physicians should retain a higher level of suspicion about abnormalities found on the digital rectal exam and about an increase in PSA.
PSA Density – A Relatively New Concept
In the past, physicians relied heavily on the absolute PSA level (or number) to decide whether prostate cancer had been eliminated, whether it had returned after treatment, and how extensive the disease was among other things.
Very quickly, however, it became apparent that just the absolute PSA level failed in some important ways.
For one, some men with normal or even low absolute PSA levels have been found to have prostate cancer.
Second, many men with very high absolute PSA levels do not have prostate cancer, but a benign, less dangerous condition such as benign prostatic hyperplasia (BPH).
Basically, the absolute PSA level does not always tell the whole story.
That is why doctors started to use other PSA values -- such as PSA velocity, PSA density, and percent-free PSA -- to get a more accurate idea of what was happening with the prostate.