Second PSMA PET Changes Treatment for Nearly Half of Prostate Cancer Patients

Reston, VA (July 7, 2026)—A second PSMA PET scan changed treatment plans for nearly half of patients whose first scan was negative, according to new research published in the July issue of The Journal of Nuclear Medicine. Findings from the repeat PSMA scans, which included both local and distant disease, resulted in a change in management for nearly 50 percent of these patients.

Managing recurrent prostate cancer after first-line treatment, such as prostatectomy or radiation therapy, remains a clinical challenge. Although PSMA PET imaging has improved disease detection, 30 percent of patients still have no detectable disease on initial imaging, even as rising prostate-specific antigen (PSA) levels suggest recurrence. Few studies have examined whether repeating PSMA PET in this situation is worthwhile.

“There is little information on the utility of repeating a PSMA PET after an initial negative scan,” said Ur Metser, BSc, MD, FRCPC, professor of radiology at the University of Toronto and head of the Division of Molecular Imaging at the Joint Department of Medical Imaging at Princess Margaret Cancer Centre in Toronto. “In our study, my colleagues and I sought to determine the benefit of a second PSMA PET scan, as well as to assess predictors for positive PSMA PET scans.”

The study included 210 patients from the Registry for Recurrent Prostate Cancer in Ontario who had more than one PSMA PET scan and whose initial scan was negative. The scan positivity rate, serum PSA, PSA doubling time, and management change after the second scan were compared with baseline data. Disease distribution was classified as local recurrence, locoregional, oligometastatic (fewer than five positive disease sites), or extensive metastatic (more than five positive disease sites).

A second PSMA PET scan revealed evidence of disease in 56 percent of recurrent prostate cancer patients who had an initial negative PSMA PET scan. A management change was necessary for nearly 50 percent of patients, in particular those with oligometastatic disease. Researchers found that repeat imaging was most likely to detect disease in patients with higher PSA levels and a PSA doubling time of less than twelve months.

“The findings in this study further strengthen the pivotal role of PSMA PET in the management of men with recurrence of prostate cancer after first-line therapy,” said Metser. “Understanding the extent of disease in patients who have initial negative PSMA PET scans provides valuable information for physicians as they create treatment plans.”

Figure 2: Imaging of 58-year-old man after radical prostatectomy for pT2a pN0 prostate cancer and negative margins, followed by salvage radiotherapy to prostate bed one year later. (A) Maximum-intensity-projection image of initial 18F-DCFPyL (PSMA) PET scan performed after biochemical failure (serum PSA level, 0.57 ng/mL) shows physiologic distribution of radiotracer with no evidence of locoregional or distant recurrence. Patient was observed after baseline PET. (B) Repeat PSMA PET scan one year later (inPET2) was performed with serum PSA level of 2.72 ng/mL, PSA velocity of 0.2 ng/mL/mo, and PSA doubling time of 5.3 mo. Maximum-intensity-projection image of inPET2 shows solitary focus of radiotracer uptake at L1. (C) Axial 18F-DCFPyL PET (right), fused PET/CT (middle), and CT (left) images from inPET2 show focus of radiotracer uptake at L1 vertebral body (SUVmax, 7.7; PSMA score, 2) with corresponding small osteoblastic lesion on CT, in keeping with metastatic deposit. Management was changed from observation to stereotactic radiotherapy to skeletal deposit.

The authors of “Utility of PSMA PET/CT After an Initial Negative Scan: Results from a Prospective Multicenter PSMA PET Registry” include Ur Metser, University Medical Imaging Toronto, Joint Department of Medical Imaging: University Health Network, Sinai Health Systems, Women’s College Hospital, Toronto, Ontario, Canada, and Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada; Glenn Baumann, Department of Oncology, Western University, London, Ontario, Canada; Mohammed Rashid and Bo Green, Quality Measurement and Evaluation, Ontario Health (Cancer Care Ontario), Toronto, Ontario, Canada; Seyed Ali Mirshahvalad, University Medical Imaging Toronto, Joint Department of Medical Imaging: University Health Network, Sinai Health Systems, Women’s College Hospital, Toronto, Ontario, Canada, and Department of Medical Imaging, Health Sciences North, Northern Ontario School of Medicine University, Sudbury, Ontario, Canada; Andres Kohan, University Medical Imaging Toronto, Joint Department of Medical Imaging: University Health Network, Sinai Health Systems, Women’s College Hospital, Toronto, Ontario, Canada; Rosanna Chan, Medical Imaging and PET Clinical Programs, Ontario Health (Cancer Care Ontario), Toronto, Ontario, Canada; and Robert Hamilton, Division of Urology, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.

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