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Curative-intent Metastasis-directed Therapies for Molecularly-defined Oligorecurrent Prostate Cancer: A Prospective Phase II Trial Testing the Oligometastasis Hypothesis. | LitMetric
University of Toronto, Department of Radiation Oncology, 149 College Street, Unit 504, Toronto, Ontario, M5T 1P5, Canada; Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 700 University Avenue, 7th floor, Toronto, Ontario, M5G 1Z5, Canada; TECHNA Institute, University Health Network, University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada. Electronic address:
Published: September 2021
AI Article Synopsis
Article Abstract
Background: The hypothesis of a curable oligometastatic prostate cancer (PCa) state remains to be clinically-proven. Conventional imaging often fails to localize early recurrences, hampering the potential for radical approaches.
Objective: We hypothesize that prostate-specific membrane antigen (PSMA)-targeted PET-MR/CT allows for earlier detection and localization of oligorecurrent-PCa, unveiling a molecularly-defined state amenable to curative-intent metastasis-directed treatment (MDT).
Design/setting/participants: Single-institution single-arm phase-two study. Patients with rising PSA (0.4-3.0 ng/mL) after maximal local therapy (radical prostatectomy and post-operative radiotherapy), negative conventional staging, and no prior salvage hormonal therapy (HT) were eligible.
Interventions: All patients underwent [F]DCFPyL PET-MR/CT. Patients with molecularly-defined oligorecurrent-PCa had MDT (stereotactic ablative body radiotherapy [SABR] or surgery) without HT.
Outcome Measurements/statistical Analysis: Primary endpoint was biochemical response (complete, i.e. biochemical 'no evidence of disease' [bNED], or partial response [100% or ≥50% PSA decline from baseline, respectively]) after MDT. Simon's two-stage design was employed (null and alternate hypotheses <5% and >20% response rate, respectively), with α and β of 0.1.
Results: Seventy-two patients were enrolled (May/2017-July/2019). Thirty-eight (53%) had PSMA-detected oligorecurrent-PCa amenable for MDT. Thirty-seven (51%) agreed to MDT: 10 and 27 underwent surgery and SABR, respectively. Median follow-up was 15.9 months (IQR 9.8-19.1). Of patients receiving MDT, the overall response rate was 60%, including 22% rendered bNED. One (2.7%) grade 3 toxicity (intra-operative ureteric injury) was observed.
Conclusions: PSMA-defined oligorecurrent-PCa can be rendered bNED, a necessary step towards cure, in 1 of 5 patients receiving MDT alone. Randomized trials are justified to determine if MDT +/- systemic agents can expand the curative therapeutic armamentarium for PCa.
Patient Summary: We studied men treated for prostate cancer with rising PSA. We found PSMA imaging detected recurrent cancer in three-quarters of patients, and targeted treatment to these areas significantly decreased PSA in half of patients.
