Thanks Chris - I've actually had three biopsies in a three month period (one TR and two TP) taking 70 core samples in all. Apart from that, no other treatment or medication at all.
I suppose my "concern" is this. As I have had a definite cancer diagnosis, and subsequent to that diagnosis the PSA level has fallen substantially (indeed to what would otherwise be considered "normal"), how safe is it to rely on the PSA test almost solely (apart from possibly 12 monthly MRI scans) as a means of signalling any change in my condition? If the answer is that I can, and therefore have nothing to worry about, I can continue on Active Surveillance without fear of missing any current "window of opportunity" as it were.
On the other hand, if the PSA test is an unsafe indicator in my case (and therefore continuing "normal" level results should not be relied on) should I be doing anything other than simply waiting 12 months for the next MRI scan?
I apologise if this sounds like I am worrying unnecessarily, but I am worrying nevertheless - and all the medical people involved simply say "it's your decision, and yours alone, whether to have active treatment or not".