Hi Yorkshire lass,
do they test his testosterone when his PSA is checked? If not, try to get that added to the next blood test as it helps to show what might be going on.
If he is still on Prostap, his testosterone should be at 0.69 or below - this is called castrate level. If his testosterone is above that point, the HT isn't working very well and they may try a different one or perhaps add Casodex (bicalutimide) to disguise the extra testosterone that is floating around. The other reason that testosterone might rise (temporarily) is if the last Prostap injection was from an off batch, was injected wrongly, stored incorrectly or the wrong dose given (it has been known for a nurse to accidentally give the one month dose rather than 3 month dose) - the hospital probably wants to wait for that next PSA test just to confirm that it wasn't a one-off blip.
If the testosterone is below 0.69 and the PSA is rising, that means the cancer has learnt to live without testosterone in which case they will probably suggest a different hormone and/or perhaps chemo again.
Great to know that he is feeling so full of beans after such a scare last year.