Hi Bee,
I think we have spoken before, but I have been in a similar position to your dad since last November. My PSA rose rapidly from 1.7 to 51.7, but after just 4 weeks on Abbi, it came down to 4.7. I went to the clinic yesterday and they told me my PSA had dropped to 3.3, so I would hope for the same for your dad.
Best wishes and good luck
Peter