Presurgical PSMA-PET Tracers Provide Treatment Plan Benefit for Patients With Prostate Cancer

By Zachary Bessette - Last Updated: December 22, 2022

The 68Ga-PSMA-11 and 68Ga-P16-093 prostate-specific membrane antigen-positron emission tomography (PSMA-PET) tracers are useful tools for surgical guidance in prostate cancer, according to new research published in Urologic Oncology: Seminars and Original Investigations.

Incontinence and impotence are common adverse effects of radical prostatectomy because of resulting injury to nerves and sphincter muscle. However, attempting to preserve nerves and muscle adjacent to prostate cancer may negatively impact surgical margins.

Clinton D. Bahler, MD, MS, of the Indiana University Department of Urology, and colleagues designed a study to measure the accuracy of 2 PSMA-PET tracers—68Ga-PSMA-11 and 68Ga-P16-093—for assessing extra-prostatic extension (EPE) at nerve bundles. Additionally, they sought to compare the PET accuracy versus standard-of-care predictors, including magnetic resonance imaging (MRI) and biopsy results.

A total of 71 men with intermediate-to-high-risk prostate cancer who underwent PSMA-targeted PET imaging prior to prostatectomy were included in the analysis. Of these men, 25 underwent 68Ga-P16-093 imaging and 46 underwent 68Ga-PSMA-11 imaging. Researchers retrospectively evaluated for assessment of EPE.

Researchers noted that 34% (n=24) of patients had pT3a disease and 23% (n=16) had pT3b disease. EPE sensitivity (87% vs 92%), specificity (77% vs 76%), and area under the curve (0.82 vs 0.84) were comparable for Ga-P16-093 and Ga-PSMA-11, respectively (P=.87).

Further MRI analysis (available in 45 patients) revealed 83% specificity and 60% sensitivity for EPE. Researchers reported that MRI sensitivity was significantly lower than PSMA PET (60% vs 90%, respectively; P=.02), but similar to PET when using a >5 mm capsular contact (76% vs 90%, respectively; P=.38).

A treatment change to “nerve sparing” was recommended for 30% (n=21) of patients based on PSMA-PET imaging, they added.

“Presurgical PSMA PET appears useful as a tool for surgical planning” and has the potential to change treatment plans to preserve nerve bundles, study authors concluded.