The PSE test is to detect whether or not there are cancer fragments in your blood. It is very expensive compared to a PSA test so it would not replace that test. Used before or after treatment, once each could be useful.

The test is not approved by the FDA for after treatment so insurance would probably not pay for it.

If the cancer goes dormant neither test can see it but it can come back.

I don’t expect the PSA to be different between tests. PSA Tests can come back with small differences I’ve done at different labs. If you were to do a PSA test and a PSE At the same time, they would probably come back very close in results. Results can vary at different times during the day.

The Decipher test is the one you take to find out the chance of a reoccurrence, Not really the PSE test. There’s a lot of discussion about that in this forum you might do a search at the top level for decipher test to get more points of view.