If the radiation in June 2019 was to the prostate bed only, i.e. SRT then doublet or triplet therapy - https://pubmed.ncbi.nlm.nih.gov/37055323/ may be something to do a literature search on and discuss with your medical team.

Your post provides some clinical data, GS and time to BCR after surgery. These two pieces of clinical history indicate high risk PCa which way warrant consideration of aggressive treatment. The other pieces of clinical data would be PSADT, PSAV, number and location of PLNs and final result of "something in your chest."

Attached is my clinical history. Similar to you GS 4+4, less than three years for BCR after what was a very "successful' surgery and subsequent pathology report. When you added my PSDAT and PSAV, well, triplet therapy it was! The difference may be the "something in your chest..."

The additional data about what the "something in my chest" along with the number and location of the PLNs lighting up in your scans is is the missing clinical data to help inform the groups assessment and feedback to you.

I would conjecture at this point as a layman, not a medical expert, you and your medical team may want to go the triplet route, ADT, an ARI, chemotherapy. If radiation is in play depending on the number and location of the PLNs, treatment of the entire PLNs should be a consideration.

Kevin