I was looking for something on post SRT nadir thresholds and it popped up so I scan read it. Mistake #1. It was just another "grab a retrospective cohort and analyse progression and outcomes based on pathology" and referred to post SRT PSA of 0.05 but not very clearly. The actual conclusion totally ignored that fact and only referred to the fact that SVI (and NOT VI) was the main concern for poor outcomes. To be fair I have only seen about half a dozen papers across the interweb that dwell on recurrence and DT.
I could not find the report again but on searching far more came up saying post SRT <0.1 (mine was 0.07) was correlated with better outcomes. This was in papers suggesting that SRT should start <0.2.
I guess there is good news in there and futher proof that the thing is a minefield.