Ablate and wait.

Top Line: Upfront prostate radiation for oligometastatic prostate cancer improves overall survival, but how should we handle metachronous oligomets after definitive prostate treatment?

The Study: On the German single-arm phase 2 OLI-P trial, 63 men received ablative radiation to all PSMA-positive oligomets (≤5) in nodes or bone. Importantly, this was a tightly defined study cohort as PSA could not be ≥10, there could be no evidence of local tumor recurrence or visceral mets and patients could not be on androgen deprivation therapy (ADT). On the other hand, “ablative” radiation was used quite loosely with the option of prescribing either 30 Gy / 10 (the norm for bone mets and used in 70% of cases) or 50 Gy / 25 (exclusively for nodal mets and used in 30% of cases). The primary endpoint of grade 2+ toxicity occurred in (surprisingly?) zero patients, despite 73% of patients receiving treatment that at least marginally overlapped with prior radiation. The secondary endpoints of median time to PSA progression was 13 months and, perhaps more clinically meaningful, time to ADT initiation was 21 months. Impressively, over one in five patients were still free of PSA progression at 3 years—again, this is without ADT. On the other hand, one-quarter of patients  had immediate PSA progression despite ablative radiation, perhaps due to unappreciated genomically-variant subclones. This means, as always, ideal patient selection leaves room for improvement. A final question to ponder is how and when this strategy should be used in the context of therapeutic Lu-177-PSMA-617 being available for a crossover population and which approach will maximize quantity and quality of survival.

TBL: For patients willing to accept a higher risk of PSA progression, ablative radiation alone for oligorecurrent (per PSMA imaging) prostate cancer can delay the need for ADT for a median of 21 months. | Hölscher, Euro Urol 2021