AS you, I had PSA failure on my first post open RRP PSA test - 0.87 and then on the second 1.1 four weeks later. Although my Gleason wasn't as high (3+4 or 7) on pathology, I did have extraprostatic extension, High Grade PIN, tumour bilateral in 4 places and also 4 positive margins. We both have aggressive cancers.
In 06 I had 36 3D Conformal Photon radiation treatments through June and July. I also started on Lupron that I have taken continually both suring and since the salvage radiation therapy. The Lupron is given to bring the Testosterone (T) down to undetectable levels, since it is believed that T feeds the tumor and makes it grow. The primary reason for the radiation is the thought that the cancer missed is still present in the prostate bed and has not begun yet to metastasize in other locations. During your prostatectomy, did the surgeon check any of your lymph nodes? You mention that one seminal vesicle was positive. I chose to have the radiation done even if my PCa was systemic. I figured that anything that might help kill it even if not all was the better way to go.
Send me a message if you want more info about what to expect from the Lupron in terms of side effects. The radiation can also have major side effects, especially impotence.
I wish you well!!