Rosie:
You do not provide other relevant information about your husband's case. You mention the surgeon said he removed all of the cancer, therefore I assume there were negative margins and the remaining cancer cells are microscopic. If you have the pathology report from surgery, as I strongly urge you to do, it may make mention of capsular penetration, extra capsular extension, or other terms referring to potential risk of spread from the tissue examination. Even if it does not say so, a serial rise in psa is a strong indicator of recurrent disease. There are a few clinical trials for men in such a position, though only a few. Yale has a Phenoxodiol trial currently.
Nonetheless, your oncologist will be a key team member. If he recommends salvage RT (radio therapy) then it may be considered. There are side effects from such therapy and most often manifest in urinary and sexual areas. This risk must be considered. A psa recurrence within a year or two after surgery, treated with RT, is less often curative than when the psa returns two years or more later. Even so, RT may provide some time until subsequent treatment decisions. It is true that the combination of therapies, in this case hormones and RT, often is more successful than the RT alone. Something about weakening the cells and making them subject to the effects of the radiation. If radiation is considered, then the decision must be made as to where to aim the beam. The prostatic fossa, or prostate bed is the most common area, though some radiologists add the draining lymph nodes as well. Your husband's case may suggest the latter.
He is a good candidate for intermittent hormone therapy, which has the chance to offer siginficant off-treatment times to some men.
There are many current research trials which suggest that in the future this disease will become more of a chronic condition like hypertension, diabetes or asthma. I hope to see such a time.