PSA Density

PSA density is defined as the PSA divided by the prostate volume.  When comparing two patients who have the same elevated PSA and different prostate volumes, the patient who has the smaller prostate is more likely to have prostate cancer.  The higher the PSA density, the more likely the patient is to have prostate cancer.

Percent Free PSA (PSA-f)

The percent free PSA (PSA-f) refers to the proportion of “free PSA” to “bound PSA” in the total PSA in the blood sample.  The free PSA circulates in the bloodstream not attached to a carrier protein.  The higher the percentage of free PSA, the lower the risk of cancer.  For instance, a free PSA of 0-10% is associated with a 56% chance of cancer while a free PSA greater than 25% is only associated with an 8% risk of cancer.