Prostate-specific membrane antigen PET/CT detects prostate cancer recurrence with higher sensitivity than multiparametric MRI after focal therapy, according to a study published August 20 in the Journal of Nuclear Medicine.
A team at the University of California, Los Angeles, evaluated gallium-68 (Ga-68) PSMA-11 PET/CT scans versus multiparametric MRI (mpMRI) for detecting and localizing recurrence after focal therapy among 112 patients, with findings suggesting a potential new role for the technique.
“Prostate-specific membrane antigen (PSMA)-targeted PET/CT (PSMA-PET/CT) has become the imaging modality of choice for staging and restaging prostate cancer,” noted co-lead authors Mahbod Jafarvand, MD, and Andrea Farolfi, MD. “However, its role in localization of recurrence after minimally invasive focal therapy has not been defined yet.”
Minimally invasive focal therapy (including high-intensity focused ultrasound, cryoablation, electroporation, and laser ablation) has emerged as an alternative for low- and intermediate-risk prostate cancer. The aim of the procedure is to reduce the morbidity of radical therapy while maintaining cancer control, the group wrote. Yet no accurate noninvasive method has been validated to evaluate treatment response, they added.
To assess PSMA-PET/CT’s potential diagnostic role, the researchers conducted a single-center retrospective analysis of 112 patients who underwent scans for suspected biochemical recurrence between 2016 and 2023, with no intervening treatment after focal therapy. Three experts analyzed whole-body PET/CT images using a per-region majority rule. In a subcohort of 39 patients with both mpMRI and prostate biopsy results within three months of PET/CT, diagnostic performance was assessed using histopathology as the reference standard.
True-positive PSMA-PET with positive MRI in 74-year-old male with prostate cancer (Gleason score of 4 + 5; left anterior and posterior apex positive cores). (A) Left posterior peripheral apical to midprostate hyposignal visible on transaxial MRI. (B) No definite CT correlate evident (white arrow). (C) Focal high PSMA expression detectable in left posterior mid to base with SUVmax of 12.4 on transaxial fused delayed pelvic PET/CT (yellow arrow). (D) Focal high PSMA expression found in left midgland to base of prostate on maximum-intensity-projection image (yellow arrow).Journal of Nuclear MedicineAccording to the findings, PSMA-PET/CT was positive in 82% of patients overall, identifying intraprostatic recurrence in 82%, pelvic lymph node involvement in 15%, and distant metastases in 9%. In the diagnostic subcohort, per-patient sensitivity was 85% for PSMA-PET/CT versus 82% for mpMRI. Lastly, all patients with a maximum standardized uptake value (SUVmax) of 10 or greater had an International Society of Urological Pathology (ISUP) grade group of 3 (intermediate-unfavorable risk) or higher, the researchers reported.
“PSMA-PET/CT effectively localizes prostate cancer recurrence after focal therapy, outperforming MRI on sensitivity,” the authors wrote.
Standardized criteria for defining biochemical recurrence after focal therapy are not yet established, and prospective studies with larger cohorts are warranted to validate these results and further define the optimal role of PSMA PET/CT after focal therapy, the group concluded.
The full article is available here.