(UroToday.com) The 2023 ESMO annual meeting included a session on prostate cancer, featuring a presentation by Dr. Dianne Bosch discussing the impact of baseline PSMA PET/CT versus CT on outcomes of radium-223 therapy in mCRPC patients. Imaging prior to radium-223 therapy is crucial for selecting metastatic castration-resistant prostate cancer (mCRPC) patients with bone-only disease. The objective of this study was to evaluate if baseline PSMA PET/CT versus CT is associated with biochemical response during radium-223.
This was a secondary analysis of the data of a prospective observational study (NCT04995614) was performed. Patients received a maximum of six cycles of radium-223 and were retrospectively divided into the PSMA PET/CT (baseline PSMA) or CT (baseline CT) group based on baseline imaging technique. All patients received baseline bone scintigraphy. Primary endpoints were alkaline phosphatase (ALP) and PSA response, defined as ≥ 30% decline from baseline. Secondary endpoints were overall survival (OS) and radiological response.
Between 2017 and 2020, 122 mCRPC patients were included: 18 (14.8%) in the baseline PSMA PET/CT and 104 (85.2%) in the baseline CT group. All baseline characteristics were comparable, and there were no significant differences in ALP or PSA response found between the groups:
The baseline CT group showed a significantly shorter OS compared to the baseline PSMA PET/CT group (12.4 vs.19.9 months, p < 0.01):
Post-therapy soft tissue involvement was detected in 29/76 patients (38.2%) that received baseline CT and post-therapy CT (baseline CT/post-therapy CT), compared to 0/18 baseline PSMA PET/CT patients. No significant difference in OS was found between baseline CT/post-therapy CT patients without soft tissue involvement and baseline PSMA PET/CT patients.
Dr. Bosch concluded her presentation discussing the impact of baseline PSMA PET/CT versus CT on outcomes of radium-223 therapy in mCRPC patients with the following concluding statements:
- Baseline PSMA PET/CT versus baseline CT does not seem to predict biochemical response during radium-223
- Nevertheless, patients in the baseline CT group had a significantly shorter OS, most likely due to underdetection of soft tissue involvement in this group
- Therefore, replacing baseline CT with PSMA PET/CT appears to be a valuable screening method to ensure in-label use of radium-223 therapy
Presented by: Dianne Bosch, MD, Radboud University Medical Center, Nijmegen, Netherlands
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2023 European Society of Medical Oncology (ESMO) Annual Meeting, Madrid, Spain, Fri, Oct 20 – Tues, Oct 24, 2023.