I'm only 51, and my HDR treatment was three years ago.
My T level was low, even prior to treatment. My PCP subscribed me T injections (at 48) and I was feeling 30; working out hard, playing basketball, etc. But my PSA doubled from 2.2 to 4.5 in that nine months.
A year ago (two years after my treatment) my T was below 200 and my PSA trended down so my uro (a specialist in the field) put me back on T injections. Last check it had risen to 380 or so.
I don't feel as good, strong, sexually aroused, etc. as I did back before my HDR when taking the T; but I think it helps and I'm in pretty good shape (need to lose 15 lbs).
I'd give it a try but do it under the care of someone with good credentials. You also might add some weight training and another day or two of racquet ball...
Father - Beat six cancers but passed at 82.
PSA: '13 - 2.5, '14 - 4.5, Jan. '15: 1.7, May '15: 1.4, Sept. '15: 2.1, Nov '15 1.3, March '16: 1.4, July '16: 0.90. Oct. '16: 0.70. Jan. '17 0.40. June '17: 0.30.
HDR Brachy 12/14 ATL