Can a PSA bounce be seen shortly after SBRT to prostate cancer oligometastases while on androgen deprivation therapy?

I would not consider it a "bounce" if it happens shortly after treatment because the timing of a post-treatment bounce is later. If the PSA is higher than pre-treatment baseline soon after metastasis-directed SBRT, then you are likely observing one of two scenarios. First, the pre-treatment baseline was not updated in the setting of a short doubling time, and perhaps you missed getting a baseline near the peak. Alternatively, the post-treatment PSA is way too soon, and you are observing a PSA ri...

I have seen a PSA bounce if the PSA is done sooner than 3 months, even while castrate. This is why I do not order a PSA until at least 3 months post any radiation, including to the primary or to metastatic sites.

PSA bounces are more common in SBRT cases. They occur much later than most of us were taught; median of 14 months, i.e., beyond the three-month follow-up time points noted. This is, of course, extrapolated from localized treatment vs oligomets such as an excellent meta-analysis from Germany (Dejonckheere et al., PMID 39557124). Overall rate in this review indicated that it also occurs much more frequently, at 33% of cases. The interesting rationale for the bounce is that there is an infiltrating...

Some additional commentary and a clarification on my comment to Dr. @Dr. First Last answer below:

The nuance here is about the target structure and purpose - for intact primary prostate treatment, I agree completely and have also noted these bounces. Literature traditionally describes bounces in a longer timeframe (9- 18 months), but it’s not clear whether PSAs were even checked sooner than 3 months post-treatment. However, I would be concerned about the case described regarding persistence/recu...

Echoing the excellent points here, I think for a patient with known metastatic disease on ADT with rising PSA 3 months after SBRT is concerning.

I have seen bounces for mets directed RT in men who are using SBRT to delay or defer ADT at 3 months, but if testosterone is truly at castrate levels, then I would be concerned for progression.

I typically repeat PSA in a short interval and discuss options for repeat imaging vs considering next-line therapy. That could be ARSI, or it could be radioliga...