Rates of PET prostate cancer imaging increased rapidly after its approval by the U.S. Food and Drug Administration (FDA), according to a study published January 3 in the Journal of Nuclear Medicine.
While rates rose from near zero in early 2021 to nearly 70% in high- and very-high-risk patients by August 2023, however, rates of positive findings were low among patients with intermediate-risk disease, noted lead author Sean Miller, MD, of the Veterans Affairs Ann Arbor Healthcare System in Michigan.
“These data confirm the utility of PSMA-PET staging in high-risk disease and suggest that additional study is needed to refine patient selection in intermediate-risk disease,” the group wrote.
Prostate-specific membrane antigen (PSMA) PET imaging with gallium-68 (Ga-68) PSMA-11 was approved by the FDA in December 2020 for the staging of newly diagnosed prostate cancer. In addition, F-18 DCFPyL (Pylarify, Lantheus Medical Imaging) was approved in May 2021 and F-18 flotufolastat (Posluma, Blue Earth Diagnostics) was approved in May 2023.
These PSMA-PET radiotracers are now incorporated in the National Comprehensive Cancer Network (NCCN) guidelines as an option for initial staging of unfavorable intermediate- or higher-risk prostate cancer, yet rates of adoption and real-world positivity rates are unknown, according to the researchers.
To address the knowledge gap, the researchers first identified all patients with newly diagnosed prostate cancer in the Veterans Health Administration system from June 1, 2020, to August 1, 2023. They analyzed demographics, staging imaging reports, and cancer-related information from electronic medical record data, as well as assessed positive findings in patients with available PSMA-PET reports.
According to the findings, during the period, among 31,838 consecutive patients newly diagnosed with prostate cancer, 4,538 (14%) were staged with PSMA-PET. The use of PSMA staging increased rapidly from near 0% in early 2021 to approximately 70% of patients with high- or very-high-risk disease by August 2023.
Among patients whose cancer had not spread to lymph nodes or other distant sites based on conventional imaging, PSMA-PET positivity rates were 5.9% for patients with favorable intermediate risk, 8.2% for those with unfavorable intermediate risk, 14% for those with high risk, and 34% for those with very high-risk disease.
In addition, compared with patients undergoing conventional staging, patients staged with PSMA-PET had higher Gleason scores (51% vs. 24%), higher baseline PSA (25% vs. 11%), and were more likely to have a higher risk of metastatic disease (14% vs. 4.3%).
“We found that patients’ risk of positive PSMA-PET findings increased with NCCN risk group, but for patients with intermediate-risk disease, rates of positive findings were less than 10%,” the researchers wrote.
The group noted that to their knowledge, this is the largest study of real-world staging of PSMA- PET uptake and positivity rates for newly diagnosed prostate cancer. Ultimately, the study provides novel information on positivity rates and may inform expected stage shifts as PSMA-PET staging continues to increase, they added.
“Further work is needed to elucidate which intermediate-risk patients most benefit from PSMA-PET staging," the researchers concluded.
The full study is available here.
