Hello again Carmel.
My husband had the permanent seed Brachytherapy and if you are interested you can click on my profile for info.
I would just point out that he was 72/3 when he had the procedure.
I believe there is a thought that the younger the person the less likely they are to be offered Permanent Seed Brachy, because, like all of the treatments, there are possible long term side effects, in this case bowel problems may occur further down the line. The younger you are the longer you would have to live with this side effect. That could be said about all of the treatments of course.
The older you are the more likely you are to develop these problems anyway so it was a risk worth taking for us.
At 55 has your husband actually been offered Seed Brachy?
There are a few others on here that had SB and I'm sure they will be along to advise you.
Just don't rush into anything is the only positive advise I would give.
Best Wishes in whatever route you take