Assessing extra-prostatic extension for surgical guidance in prostate cancer: Comparing two PSMA-PET tracers with the standard-of-care

Background: Incontinence and impotence occur following radical prostatectomy due to injury to nerves and sphincter muscle. Preserv-ing nerves and muscle adjacent to prostate cancer risks positive surgical margins. Advanced imaging with MRI has improved cancer locali-zation but limitations exist. Objective: To measure the accuracy for assessing extra-prostatic extension at nerve bundles for 2 PSMA-PET tracers and to compare the PET accuracy to standard-of-care predictors including MRI and biopsy results. Materials and Methods: We studied men with PSMA-targeted PET imaging, performed prior to prostatectomy in men largely with intermediate to high-risk prostate cancer, and retrospectively evaluated for assessment of extra-prostatic extension with whole-mount analy-sis as reference standard. Two different PSMA-PET tracers were included: 68Ga-PSMA-11 and 68Ga-P16-093. Blinded reviews of the PET and MRI scans were performed to assess extra-prostatic extension (EPE). Sensitivity and specificity for extra-prostatic extension were com-pared using McNemar's Chi2. Results: Pre-operative PSMA-PET imaging was available for 71 patients with either 68Ga-P16-093 (n = 25) or 68Ga-PSMA-11 (n = 46). There were 24 (34%) with pT3a (EPE) and 16 (23%) with pT3b (SVI). EPE Sensitivity (87% vs. 92%), Specificity (77% vs. 76%), and ROC area (0.82 vs. 0.84) were similar between P16-093 and PSMA-11, respectively (P = 0.87). MRI (available in only 45) found high spec-ificity (83%) but low sensitivity (60%) for EPE when using a published grading system. MRI sensitivity was significantly lower than the PSMA-PET (60% vs. 90%, P = 0.02), but similar to PET when using a > 5 mm capsular contact (76% vs. 90%, P = 0.38). A treatment change to "nerve sparing " was recommended in 21 of 71 (30%) patients based on PSMA-PET imaging. Conclusions: Presurgical PSMA-PET appeared useful as a tool for surgical planning, changing treatment plans in men with & GE;4+3 or multi-core 3+4 prostate cancer resulting in preservation of nerve-bundles. (c) 2022 Elsevier Inc. All rights reserved.