Instead of starting a new discussion, I hope it's okay to piggyback on this one since my circumstance is similar, just not restricted to brachy as the radiation format.
I just received biopsy results and spoke to my urologist three days ago, who recommends either surgery or radiation. I'm a bit agog in deciding which to favor.
I'm 71, in pretty good shape and health apart from dealing with chronic fatigue since my first(!) Covid-19 infection about a year ago (AKA Long Covid).

This spring, after a blood test showing 7.2 ng/mL level of PSH, I was referred to a urologist, who found a nodule, and referred me to imaging, for a contrast MRI.
It revealed a .5ml lesion abutting the capsule, but apparently fully contained therein.
I subsequently underwent a biopsy, and here are the results:
(They are all Adenocarcinoma)
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C: R3 right lateral mid: Gleason pattern 3 + 5 (5%) =8, grade group 4, 5.5 mm in 13.5 mm core, 40% of tissue.

D: R4 right medial mid: Gleason pattern 3+3=6, grade group 1, discontinuous 0.4 mm and 0.3 mm foci in 14 mm core, 5% of tissue.

I: L3 left lateral mid: Gleason pattern 3 + 4 (20%) =7, grade group 2, 2 mm in 10 mm core, 20% of tissue.

K: L5 left apex lateral: Gleason pattern 3 + 4 (20%) =7, grade group 2, discontinuous 0.4 mm and 0.2 mm foci in 9 mm core, 5% of tissue.
-Perineural invasion present.

M: Target 1,:, Gleason pattern 3 + 5 (5%) =8, grade group 4, involving 4 of 5 cores, 11 mm in 43 mm core, 25% of tissue.
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I have to admit I'm a bit confused about the final "M: Target 1" as I'm uncertain just where that was from, or if it's a generalization of the bunch. Forgot to ask my urologist about that.
He seemed to discount the Perineural invasion as insignificant.
He did say that the cancer does appear to be contained just within the organ, but that it is somewhat aggressive, and needs to be dealt with "soon", but he was agnostic about whether surgery or radiation would be best. I asked about focal radiation, but apparently the cancer is a bit too dispersed for that to be effective. He also discounted brachytherapy as appropriate.

I'm dealing with the local University of California health system here, which I understand is well-regarded, and he has referred me to a surgeon there (turns out to be the same one who did the biopsy, coincidentally), as well as their hospital in La Jolla that is equipped for radiation therapy.

I'm nervous about the possibly greater chances of urinary and ED problems (I have a wife) with surgery, but the higher chance of bowel problems with radiation certainly gives me pause, along with its side effect of (more, in my case) fatigue.
I think I'm leaning towards the surgery option--they do have the amazing DaVinci (or was it Cuisinart..?) robotic thingie--and the finality of it appeals, but, again, I'm uncertain, and would love to hear from some of you knowledgeable and experienced fellows for your perspectives.
Thanks so much!