This plot shows the PSA relapse rate after RT and ADT, for Intermediate and High Risk men, comparing different levels of testosterone nadir ( 50 nd/dL). (ref: 2019)
The best outcomes are significantly associated with a lower testosterone nadir ( < 20 ng/dL), and the relationship appears to be roughly linear; heading toward a zero relapse rate for a testosterone nadir = 0.
This may be well-known to many of you, but it was new to me.
The prior definition of castration being < 50 ng/dL probably needs to redefined to < 20 ng/dL. (I read that the level of 50 ng/dL may be an artifact representing the lowest limit that testosterone could be accurately measured many years ago. That makes sense to me).
Question about PSA Nadir
What is PSA NADIR for ADT treatment?
PSA back on the rise - or hitting Nadir?
Falling PSA but rising Testosterone
