Re: radiation and hormone therapy after RP
If his PSA is too low right now to show up on the C11-Choline PET scan it is certainly too low to show up on the bone scan and CT, so imho, it is pointless. You may want to check with your insurance company to see how many and which imaging tests they will pay for.
Yes, he would have to have the test done at the Mayo clinic in MN -- that's the only place doing it right now. C-11 has a half-life of 20 minutes, so it must be done on site. However the test is non-invasive and would take at most a few hours. There are a few places doing a similar test using C-11 Acetate -- UCLA, and facilities in Kansas and Arizona, as I recall -- but they all would require some out-of-state travel for you.
Here's the dilemma: you can wait for his PSA to rise to the point where it would be detectable on the C-11 Choline PET (I think they are looking for something over 1.5 if I remember correctly). If they then find the mets and they are few in number, they can pick them off with SBRT and potentially cure him with very few or no side effects. However, there is a risk to this strategy. If the cancer were high grade (Gleason score 8-10), it may escape the pelvic region if he is not on HT, but with a 4+3 his odds are better. Salvage RT has the greatest chance of success when the PSA is less than .5. There is no easy answer. You have to carefully weigh the risks against the potential benefits, and decide what you both are willing to live with.
The whole point of neoadjuvant hormone therapy is to start it before the radiation. It makes the cancer more sensitive to the killing effects of the radiation. There is some evidence to support this, but it's not a certainty. Continuing HT afterwards is even more problematic -- if the actual cancer killing is accomplished by the radiation, what is the point of continuing the HT afterwards? Yet there is some evidence it may help, and many cancer centers continue the HT for up to 2 years afterwards. No one really knows for sure. There is a lot of uncertainty in this area. If you decide to forego the C-11 PET scan, you may want to enter a clinical trial that uses other means aside from traditional HT (e.g., Taxotere or Abiraterone) to sensitize the cancer.
I wish I could give you more certainty on these issues, but I don't think anyone can.