Hi . First, let me say that it is great that your husband has you advocating and seeking information on his behalf. Second, you mention a Gleason of three, but these scores are actually a two number combination (the primary and secondary finding) and total, such as 3+3=6 or 3=4=7. The scores go up to a maximum total of 10 and anything below 6 is not considered cancer (six is an interesting debate). I mention all this because the total can make a difference in treatment options. For example, a 6 can often have an option of active surveillance, as opposed to treatment (see here for more information: https://prostatecancer.net/treatment/active-surveillance).
It is good to hear that your husband is scheduled for a PET Scan and I assume it is a PSMA PET, which is the gold standard in spotting any cancer spread (see: https://prostatecancer.net/treatment/psma-targeted-pet-imaging). The outcome of this will also help determine treatment options.
Assuming no spread, offered a lot of good information. As you noted, there have been a lot of advances. This article gives an overview of the various types of radiation therapy: https://prostatecancer.net/treatment/radiation-therapy. Concerning the side effects, different types of therapy reduce to profile of some, but each person's issues can be different. My father-in-law had a combination of Cyberknife radiation and traditional radiation with few side effects, but others may have urinary and/or ED issues. As Mike55 said, getting a couple of opinions on treatment options can be helpful. Wishing you and your husband the best and please feel free to keep us posted and to ask additional questions. Richard (Team Member)