Abstract
The EMPIRE-1 (Emory Molecular Prostate Imaging for Radiotherapy Enhancement-1) trial reported a survival advantage in recurrent prostate cancer salvage radiotherapy (SRT) guided by 18F-fluciclovine PET/CT versus conventional imaging. We performed a post-hoc analysis of the EMPIRE-1 cohort stratified by protocol-specified criteria, comparing failure-free survival (FFS) between study arms. Methods: EMPIRE-1 randomized patients to either conventional imaging (Bone scan plus abdominopelvic CT or MRI) only SRT planning (arm A) or conventional imaging plus 18F-fluciclovine PET/CT (arm B). Randomization was stratified by PSA (<2.0 ng/mL versus ≥2.0 ng/mL), adverse pathology, and androgen-deprivation treatment (ADT) intent. We sub-divided patients in each arm using the randomization stratification criteria and compared FFS between patients’ sub-groups across study arms. Results: Eighty-one and 76 patients received per-protocol SRT in study arms A and B, respectively. The median follow-up duration was 3.5 years (95% CI: 3.0 – 4.0). FFS was 63.0% and 51.2% at 36- and 48-months, respectively, in arm A and 75.5% at both 36- and 48-month follow-ups in arm B. Among patients with PSA <2ng/mL (mean = 0.42 ± 0.42), significantly higher FFS was seen in arm B than arm A at 36-months (83.2%, 95%CI: 70.0-91.0 versus 66.5%, 95%CI: 51.6-77.8, p<0.001) and 48-months (83.2%, 95%CI: 70.0-91.0 versus 56.2%, 95%CI: 40.5-69.2, p<0.001). No significant difference in FFS between study arms in patients with PSA ≥2ng/mL was observed. Among patients with adverse pathology, significantly higher FFS was seen in arm B than in arm A at 48-months (68.9%, 95%CI: 52.1-80.8 versus 42.8%, 95%CI: 26.2-58.3, p<0.001) though not at 36-months follow-up. FFS was higher in patients without adverse pathology in arm B vs arm A; 90.2%, 95%CI: 65.9-97.5 versus 73.1%, 95%CI: 42.9-89.0, P = 0.006, at both 36- and 48-months. Patients in whom ADT was intended in arm B had higher FFS than those in arm A with the difference reaching statistical significance at 48-months (65.2%, 95%CI: 40.3-81.7 versus 29.1, 95%CI: 6.5-57.2, p<0.001). Patients without ADT intent in arm B had significantly higher FFS than patients in arm A at 36-months (80.7%, 95%CI: 64.9-90.0 versus 68.0%, 95%CI: 51.1-80.2) and 48-months (80.7%, 95%CI: 64.9-90.0 versus 58.6%, 95%CI: 41.0-72.6). Conclusion: The survival advantage due to the addition of 18F-fluciclovine PET/CT into SRT planning is maintained regardless of the presence of adverse pathology or ADT intent. Including 18F-fluciclovine PET/CT into SRT leads to survival benefits in patients with PSA <2 ng/mL, but not in patients with PSA≥ 2 ng/ml.
- Oncology: GU
- PET/CT
- Radiation Therapy Planning
- 18F-fluciclovine PET/CT
- Failure-Free Survival
- Prostate Cancer
- Prostate-Specific Antigen
- Salvage Radiotherapy
- Copyright © 2022 by the Society of Nuclear Medicine and Molecular Imaging, Inc.