Prostate Cancer Treatment Adjusted by Second PSMA PET Scan
A new study indicates that a second prostate-specific membrane antigen (PSMA) PET scan can significantly alter treatment plans for nearly half of patients whose first scan came back negative. This research, featured in the July edition of The Journal of Nuclear Medicine, found that repeat scans revealed conditions in almost 50% of patients previously deemed disease-free.
Recurrent prostate cancer management post-first treatment—like surgery or radiation—poses a substantial challenge. Despite advancements in PSMA PET imaging, about 30% of patients still show no detectable disease when first scanned, even as rising prostate-specific antigen (PSA) levels hint at a possible recurrence. However, there’s been limited research on whether repeating the scan is beneficial in these scenarios.
Dr. Ur Metser, a radiology professor at the University of Toronto, stated that the existing literature doesn’t adequately address the effectiveness of conducting a second PSMA PET after an initial negative result. His team aimed to evaluate the benefits of this follow-up imaging and identify factors that might indicate a positive outcome.
The study reviewed data from 210 patients in Ontario’s Registry for Recurrent Prostate Cancer, all of whom had more than one PSMA PET scan, with their initial one registering negative. Researchers compared the positivity rate of the repeat scans along with serum PSA levels, PSA doubling times, and any management changes afterward. They categorized disease distribution into local recurrence, locoregional, oligometastatic (fewer than five affected sites), or extensive metastatic (over five affected sites).
The results showed that the second PSMA PET scan detected disease in 56% of patients who had tested negative initially. Furthermore, nearly half of these patients required a shift in their treatment strategy, particularly those diagnosed with oligometastatic disease. The study revealed that follow-up imaging was more likely to pick up disease in patients exhibiting higher PSA levels and a doubling time of under 12 months.
Dr. Metser commented that these findings reinforce the crucial role that PSMA PET plays in managing recurrent prostate cancer after initial therapies. Understanding the disease extent in patients who initially show negative results equips physicians with essential information for more effective treatment planning.
Publication Details
Ur Metser et al, Utility of PSMA PET/CT After an Initial Negative Scan: Results from a Prospective Multicenter PSMA PET Registry, Journal of Nuclear Medicine (2026). DOI: 10.2967/jnumed.126.272204
