Some things are still uncertain.

PSA = or < 0.1 -0.2
Depending how the RP is done, e.g. nerve sparing, could some prostate tissue be left behind? I recall a discussion amongst four urologists on what to do with someone with PSA levels like this. One replied: I always ask the pathologist if they saw the prostate capsule membrane in the prostate that was removed. The implication is if they don't see it, some tissue could remain which might account for the tiny amounts of PSA. The key is looking for rising levels. I don't have enough information to determine if the PSA is rising.

Next: What is the reproducibility of the laboratory's PSA method at such levels? Are 0.04 and 0.09 truly different? I suspect these levels are analytical challenges, You would have to run both specimens in the same assay to be more certain. If the lab runs a QC specimen in this range, the analytical range should be known.

PSMA PET. Mine showed all cancer confined to the prostate. I hope it is true. On the other hand, what do we know about the analytical detection level of a PSMA PET for prostate cells? Perhaps it has been studied; I don't know. This is very new technology. One thing I'm fairly certain of: a negative PSMA PET does not rule out extra capsular disease. It likely only gives you probabilities of disease/disease free, neither of which has likely been established yet.

BTW, I chose radiation rather than RP. That decision too is a bit of a crap shoot as far as disease is concerned.