Archer48-
The Vancouver Prostate Centre is excellent, so you have some very good choices there. Martin Gleave is on anyone's list of top urologists, and would be a great choice. You can fill out a nomogram like the one below to get a feeling for the odds that surgery would be successful:
/www.mskcc.org/nomograms/prostate/pre-opSo your expected 10-yr probability of being free from recurrence is 83% if you go with surgery.
I think they now offer both kinds of brachytherapy there - low dose rate (seeds) and high dose rate (temporary implants). Because of your relatively high grade cancer which is predominantly pattern 4 (4+3), there is a relatively high risk that it is outside of the area that seeds alone could cure. I think most seed ROs would also include external beam radiation to treat the parts that seeds can't reach effectively. In fact, the seminal study proving the efficacy of brachy boost therapy for intermediate risk guys like you was done in Vancouver (it was called the ASCENDE-RT trial). For men with intermediate risk PC, the 9 year probability of being free from recurrence was
94% for those who received the brachy boost therapy.
/pcnrv.blogspot.com/2017/03/brachy-boost-gold-standard-for.htmlBecause the side effects of brachy boost therapy are higher than brachy monotherapy, some ROs are using high dose rate brachytherapy (HDR-BT) as a monotherapy for intermediate risk men. HDR-BT, unlike LDR-BT, can treat an area outside of the prostate capsule. This seems to have equally excellent oncological outcomes with less toxicity.
The risk of second cancers due to radiation exposure is low:
/pcnrv.blogspot.com/2016/08/the-real-risk-of-secondary-malignancies.htmlSalvage therapy is not much of an issue with cure rates of 94%, and for most of the remaining 6%, the recurrences were probably not local -- they were metastatic and could not have been cured. For the remainder, if they were local-only recurrences, they could potentially be cured with focal salvage radiation or focal salvage ablation. They have a better side effect profile than salvage surgery after radiation. All salvage therapies, after RP or RT, have a higher probability of side effects than either treatment alone. It is best to make the decision on what is most likely to cure you.