I don't know if this will be of any help but here goes, When I was diagnosed with Prostate Cancer about 18 months ago at age of 67 years, I was straight away given injections of Prostap Hormone therapy. When the Radiotherapy was due to start the injections were stopped and at that time my PSA was down to 1-0 after the 37 doses of Radiotherapy my PSA was "undetectable" according to the Oncologist. Last week I had to go for my 6 month check up and PSA test, again I was told undetectable, but the remains of the Prostap can apparently stay in the body for up to 18 months or so, when I next go for my next 6 month test (December) I was told that the Proistap will have completely gone but to expect a slight rise in my PSA level, back up to 1-0 or 1-5. This according to the urologist and Oncologist is nothing to worry about and to be expected.
I hope that this may be of some help to you.