Hi
I think it would depend on the treatment plan. I have taken my 3 monthly hormone injection (decapetyl) with me to Turkey and had it administered there. Cost a minimal 50p to have it injected in a very modern and well equipped hospital. No queues, just turned up and was seen by nurse. Just needed to make sure it was kept within required temperature range. They would also do blood tests, scans etc.
We went to California for a month Dec 2013 to Jan 2014 to stay with my wife's daughter.
I have advanced PC with spread to bones (PSA was c. 250 on diagnosis but came down with treatment) and had trouble getting travel insurance but got it at a reasonable price through AXA PPP. My consultant had to say I was fit to travel and on the balance of probability would be ok for 12 months.
I am 55 and relatively fit. We live as normally as possible and are doing as much as we can whilst we are able to.
Best wishes to your father.
Martin