Oligomets and SBRT: "Whack a Mole"?

[FrankyB4]

"PSMA-PET guided SBRT for oligo-metachronous PCa recurrence in appropriately triaged patients results in excellent local control, low toxicity and over 50% ADT free at 5 years."

See "Long-term outcomes of SBRT for PSMA PET detected oligometastatic prostate cancer"

ro-journal.biomedcentral.co...

“If PSMA PET–CT imaging is positive without conventional correlates that would have

been independently seen on CT or [99mTc]Tc-MTD bone scintigraphy, there may be a knee

jerk reaction to label them as metastatic in the conventional sense. Then clinicians will be

considering agents approved in the metastatic castration sensitive prostate cancer (mCSPC)

such as docetaxel, apalutamide, enzalutamide, or abiraterone.

Understanding the natural history of BCR based on existing data should be used to

inform clinicians about their management decisions in patients who have conventional

imaging devoid of metastatic disease despite PSMA scan findings.

However, if conventional imaging and PSMA PET–CT imaging results are conflicting, interpreting

these results with the knowledge of retrospective studies will be required until prospective

evidence is available to prevent overtreatment and optimize patient care. Upon reviewing

existing data, it becomes more evident that caution should be used when labeling PSMA

positive patients as equivalent to mCSPC and equating them to populations in mCSPC

trials, when it is very likely that the indolent nature of recurrent disease may not be as

impacted from treatment intensification of ADT-based combinations. Deploying such ADT

combinations earlier may have more ambiguous net benefits to patients when weighed

against the toxicity of such regimens which may need to be administered for a decade or

more in some cases.”

See "The Continuum of Metastatic Prostate Cancer: Interpreting PSMA PET Findings in Recurrent Prostate Cancer."

pubmed.ncbi.nlm.nih.gov/353...

[GP24]

In the first study 50% of patients did not start with ADT within 5 years after radiation. However, "with median time to BF of 1.1 years." So the median of the patients had biochemical failure, i.e. PSA over 2.0 ng/ml, within 1.1 years.

[FrankyB4 in reply to GP24]

Yes, but 32% of the patients had "further curative-intent radiation following their first BF after SBRT, including subsequent SBRT.

[GP24 in reply to FrankyB4]

Here is a study about repeated SBRT radiation of mets:

ro-journal.biomedcentral.co...

As you can see, sometimes the new mets grow at places where they cannot be radiated.

[FrankyB4 in reply to GP24]

That makes sense.

Here is a paper relating to a recurrent oligo patient ( retired doctor) who rejected ADT and has pursued multiple SBRT for the last 11 years utilizing PSMA scans, or their predecessors, each time his PSA rose to locate the target:

Long-Lasting Palliation of Bone Oligometastatic Prostate Cancer After Repeated Stereotactic Body Radiotherapy

pubmed.ncbi.nlm.nih.gov/345...

[j-o-h-n]

FrankyFr

Good Luck, Good Health and Good Humor.

j-o-h-n Wednesday 09/13/2023 6:04 PM DST