Earlier this week the Food and Drug Administration (FDA) approved Gallium 68 PSMA-11 as the first prostate membrane specific antigen based tracer for PET CT imaging. The tracer was specifically approved to aid in the detection of metastatic prostate cancer. Despite the approval, guidelines have yet to clarify the role of PSMA versus conventional imaging.
Dr. Cooperberg began the session by providing the argument against the widespread adoption of PSMA-PET imaging into our current prostate cancer algorithms. He acknowledged the abundance of literature demonstrating superior detection rates with PSMA-PET over conventional imaging, even in the setting of very low prostate specific antigen (PSA). However, he cautioned that this was causing a large stage migration and overtreatment. Referencing famed comedian Will-Rogers, he noted that by reclassifying previously occult metastatic disease, one would improve the outcomes of both cohorts without actually changing the outcomes for any individual patient.
Furthermore, the literature, which is the bedrock of current advanced prostate cancer treatment algorithms, is based on trials that used conventional imaging to define metastatic disease. Detection of disease earlier may end up exposing patients to earlier and prolonged therapies without any benefit in overall survival. In the salvage setting, he went on to state that current evidence is lacking to support the role of PSMA-PET imaging and that further trials were desperately needed within this space.
Dr. Dorff, had the counterpoint position, arguing for the adoption of this technology. She began her discussion focusing on the setting of high-risk local disease. Citing Dr. Hofman’s article published earlier this year in The Lancet1, she discussed the superior detection rates with PSMA-PET over conventional imaging as a major strength of the technology for treatment planning purposes.
Next, she discussed the role of PSMA in the patient with early biochemical recurrence. In this setting PSMA detects metastatic disease approximately 50% of the time, assisting in the proper identification of patients that would benefit from salvage radiation therapy while sparing those that would not. Furthermore, there is a growing trend for the treatment of oligometastatic disease with radiation. PSMA-PET is both useful in identifying these lesions, as well as monitoring treatment response. She concluded her talk stating that the initial data is very promising for PSMA, but did acknowledge the need for level one data to further define the role of this technology.
Presented by: Matthew R. Cooperberg, MD, MPH, Professor of Urology; Epidemiology & Biostatistics, Helen Diller Family Chair in Urology, University of California, San Francisco, San Francisco, California & Tanya B. Dorff, MD, Associate Clinical Professor, Department of Medical Oncology & Therapeutics Research, City of Hope, Duarte, California
Written by: Written by: Adrien Bernstein, MD, Society of Urologic Oncology Fellow, Fox Chase Cancer Center, Fox Chase Cancer Center, Philadelphia, PA, during the 2020 Society of Urologic Oncology Annual Meeting – December 2-5, 2020 – Washington, DC
1. Hofman, M. S. et al. Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): a prospective, randomised, multicentre study. Lancet 395, 1208–1216 (2020).