When most of the PSA in the blood is bound with limited free PSA, it is a strong marker that cancer cells are leaking PSA into the bloodstream.

“when most of the PSA that you have in your blood is um bound very limited amounts of free PSA that's a strong marker that there's something going on I.E that cancer cells are leaking the PSA into the bloodstream”

“so if the percent free PSA is over 18 to 20 then you can be rest pretty well assured that that's likely not coming from some aggressive bulky tumor”

“we really want to use the percent free PSA to discriminate y individuals who have elevated PSAs and having to discriminate between elevated because of BPH and elevated because of a cancer”

“as you get older your prostate gets bigger so you we begin to use that in in as you get older and your prostate gets bigger you can have a proportional rise in total PSA in your blood stream just because your prostate is bigger and it's leakier but you can easily tease that out by looking at the percent free PSA”