(UroToday.com) The 2023 GU ASCO annual meeting included a session on prostate cancer, featuring a presentation by Dr. Miles Hsu discussing concordance with conventional imaging for 18F-DCFPyL PET in first biochemical recurrence and initial staging. 18F-DCFPyL recently gained FDA approval for the staging of biochemically recurrent prostate cancer.
After 18F-DCFPyL became available at the Abramson Cancer Center NCI-Designated Comprehensive Cancer Center, 164 prostate cancer patients underwent imaging by May 2022. Given its novelty, the clinical utility of 18F-DCFPyL versus conventional imaging is not well-defined. Dr. Hsu and colleagues evaluated the concordance and treatment impact of 18F-DCFPyL compared to conventional imaging in suspected first biochemical recurrence and upstaging rates of 18F-DCFPyL in initial staging.
The electronic medical record was queried to identify 18F-DCFPyL scans performed at the Abramson Cancer Center. The authors selected patients with PSA recurrence after definitive frontline therapy or those undergoing initial staging. Conventional imaging was within 3 months of 18F-DCFPyL. Concordance between conventional imaging and 18F-DCFPyL was assessed, with probable disease defined through assessments by the radiologist and treating oncologist and the clinical setting. Provider notes were used to capture anticipated treatment plans before and after 18F-DCFPyL.
For suspected biochemical recurrence 30 patients had conventional imaging and 6 had two types of conventional imaging. The majority (n = 20) were MRIs of the prostate/pelvis, and the remainder were nuclear bone scans (n = 4), body CTs (n = 4), 18F-fluciclovine scans (n = 3), FDG-PET (n = 1), and spinal imaging (n = 3). Discordant findings were present for 12/30 patients in shared imaging fields, of which seven had likely disease captured solely on 18F-DCFPyL, one instance of disease missed on 18F-DCFPyL, and four instances where findings of uncertain malignant potential on conventional imaging were not tracer-avid on 18F-DCFPyL. The missed disease on 18F-DCFPyL was a PIRADS 4 prostate lesion captured on MRI. In this group, four cases of pelvic nodal lesions were identified on 18F-DCFPyL and not MRI. The following figure shows several examples of usage of 18F-DCFPyL in equivocal lesions:
18F-DCFPyL influenced treatment plans in 4/30 cases. Therapy was selected as follows:
- Local salvage radiation was chosen after rule-out of systemic disease
- Radiation was restricted to the prostate bed after a culprit lesion was found
- The observation was chosen (n = 2) after disease was ruled out on PSMA-PET
For initial staging, 15 patients were thought to have prostate-only disease. On 18F-DCFPyL, 3/15 were upstaged to distant metastatic disease and 2/15 were upstaged to pelvic nodal disease. Three patients were thought to have extra-prostatic pelvic disease, of which 1/3 were upstaged to distant metastatic disease on 18F-DCFPyL.
Dr. Hsu concluded this presentation discussing concordance with conventional imaging for 18F-DCFPyL PET in first biochemical recurrence and initial staging with the following take-home messages:
- In the biochemical recurrence setting, in which disease is often low volume, 18F-DCFPyL frequently adds valuable guidance
- In this cohort, 18F-DCFPyL captured additional pelvic nodal disease and helped clarify equivocal imaging, limiting unnecessary treatment
- For initial staging, the 33% of patients upstaged is substantial, and further data will show whether subsequent changes in management affect outcomes
- Limitations include inability to verify disease histologically and to forecast treatment decisions if PSMA-PET were not available
Presented by: Miles Hsu, Abramson Cancer Center, Penn Medicine, Philadelphia, PA
Co-Authors: Xinhe Shan, Austin Pantel, Samuel U Takvorian, Jeffrey Shevach, Vivek Narayan, Neha Vapiwala, David J. Vaughn, Naomi B. Haas
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2023 Genitourinary (GU) American Society of Clinical Oncology (ASCO) Annual Meeting, San Francisco, Thurs, Feb 16 – Sat, Feb 18, 2023.