PSMA PET-CT Provides Staging Benefits Over MRI

TOPLINE:

Fluorine-18 prostate-specific membrane antigen (PSMA)-1007 PET/CT improves locoregional staging compared with MRI in patients undergoing surgery for intermediate and high-risk prostate cancer.

METHODOLOGY:

1. PSMA PET/CT has high PSMA affinity, higher resolution, and a longer half-life than traditional radioligands, and minimal urinary excretion.
2. In this phase 2 trial, the researchers enrolled 134 men with intermediate or high-risk prostate cancer who were scheduled to undergo surgery between March 2022 and June 2023.
3. Participants underwent both PSMA PET/CT and MRI within 2 weeks of each other but at least 5 days before radical prostatectomy.
4. Of these, 127 (95%) had tumors of Gleason grade group 2 or 3, and 65 (49%) had extraprostatic extension (T3a or T3b). Most (88%) scored three or higher on a prostate imaging system.
5. The primary outcome was the correct identification of prostate cancer tumor stage. The secondary outcomes were identification of the dominant nodule, laterality, extracapsular extension, and seminal vesicle invasion.

TAKEAWAY:

1. PSMA PET/CT scans correctly identified the final pathological tumor stage in 45% of patients compared with 28% in case of multiparametric MRI (P = .003).
2. Additionally, PSMA PET/CT was superior in spotting the dominant nodule (94% vs 83%), laterality (64% vs 44%), and extracapsular extension (75% vs 63%). All differences were also significant.
3. However, PSMA PET/CT scans were not better than MRI in detecting spread to seminal vesicles (91% vs 85%; P = .07).
4. PSMA-PET/CT also showed higher sensitivity for extracapsular extension (58% vs 33%), seminal vesicle invasion (57% vs 33%), and lymph node metastasis (50% vs 25%). They also detected more Gleason grade 2 or higher nodules (29% vs 11%) than did MRI.

IN PRACTICE:

"High-risk features such as extracapsular extension are critical to identify on imaging before radical prostatectomy as their presence alters the surgical approach," the authors wrote. They also added that accurate identification of unilateral vs bilateral disease are "important for novel treatments for patients with prostate cancer, such as focal therapies."

SOURCE:

This study was led by Nikhile Mookerji, MD, Division of Urology, Department of Surgery, University of Alberta, Edmonton, Alberta, Canada, and published online in JAMA Oncology on July 1, 2024.

LIMITATIONS:

The absence of whole-mount specimens for pathological analysis and the lack of a standardized template lymph node dissection during radical prostatectomy warrant careful interpretation of the findings.

DISCLOSURES:

The study was supported by the Canadian Urological Association and jointly by the University Hospital Foundation and Royal Alexandra Hospital Foundation. The authors did not declare any conflicts of interest.