Welcome to you and your dad to the Board!
Did the surgeon advise your dad before the surgery that the odds of cure with surgery, based on a Gleason 8 and PSA greater than 10 were about 50% at best and possibly half that? These odds are based on the very well known and widely used Partin Tables. Do you know how much experience your dad's surgeon has had doing Da Vinci robotic
prostatectomies? The doctor seems quite experienced based on your initial post, but I'm having trouble figuring out why he was surprised the surgery did not work based on the odds.
I'm just learning about interfering antibodies that distort PSA results. They seem to exist but be extremely rare. I'm doubtful they will prove useful, but it is another base to touch, and your dad has now ruled out that explanation.
I'm a layman, not a medical professional (no enrolled medical education), but I have learned that the lymph nodes that are sometimes checked during prostatectomies are just a sample of lymph nodes that could contain prostate cancer. Moreover, CT scans only catch rather large tumors, about the size of a pea (and larger) as I recall; it is quite possible your dad has cancer in a lymph node that was not sampled and that is too small to be picked up by a CT scan. Nor are conventional bone scans all that sensitive; it takes about 10% of cancer involvement at a site before the conventional (technetium isotope) bone scan will pick up a likely problem. Therefore, unfortunately, it is quite possible your dad has some prostate cancer that is beyond the prostate and causing that unexpected PSA.
I'm glad he is consulting at Johns Hopkins, at least as far as understanding the problem is concerned. On the other hand, in my opinion as a layman survivor of 12 1/2 years of a challenging case treated solely with intermittent triple androgen deprivation therapy (IADT3, aka hormonal therapy, plus supportive drugs and lifestyle tactics but no surgery, radiation, etc.), having consulted with Johns Hopkins experts and being familiar with experiences of some patients treated there, I am not impressed that Johns Hopkins consistently uses the most effective ADT approaches. Among other problems, in my view, some surgeons do not believe in using ADT early. Some do not understand the importance of monitoring and greatly reducing DHT (dihydrotestosterone) as well as testosterone. The experts in ADT I have followed for years believe in using ADT fairly soon when the patient is strong but the cancer is still weak. When your dad sees someone at Johns Hopkins, I recommend he consult a medical oncologist there rather than a surgeon.
He might also want to consult a radiation oncologist. Salvage radiation is another option. Has your dad talked to anyone about that? ADT is typically combined with radiation for higher risk cases. It would first be important to figure out if the cancer is still in range of radiation. The fairly new Na (sodium) 18F PET/CT bone scan is much more reliable than the technetium bone scan for checking for any bone mets. There are a couple of scans, C11 choline and feraheme Ultrasmall Superparamagnetic Iron Oxide high resolution (3 Tesla) MRI scan for lymph nodes that are quite effective for checking for prostate cancer in lymph nodes. The latter is just emerging and is being used by just a few doctors.
Is your dad familiar with nutrition and other lifestyle tactics to help make the job easier?
There is great hope for prostate cancer patients treated these days, even for those for whom the initial treatment failed to cure the cancer. Well done ADT alone has given many of us many years of excellent control, and for most of us the side effect burden can be managed and is quite tolerable.