Can Ga-PSMA-11 PET/CT predict pathological upgrading of prostate cancer from MRI-targeted biopsy to radical prostatectomy?

Purpose: Prostate-specific membrane antigen (PSMA) positron emission tomography (PSMA-PET) is an ideal tool for staging and restaging of prostate cancer (PCa). This study was designed to investigate the prognostic role of preoperative Ga-PSMA-11 PET/CT in predicting pathological upgrading from multiparametric magnetic resonance imaging-targeted biopsy (mpMRI-TB) to final radical prostatectomy (RP) specimens in patients with localized PCa.

Methods: A total of 67 biopsy-confirmed localized PCa patients with mpMRI and Ga-PSMA-11 PET/CT prior to RP were included. Clinical and imaging characteristics derived from mpMRI and PET/CT were compared in patients with or without pathological upgrading. Predictors for pathological upgrading were evaluated by using univariate and multivariable analyses. A prediction model was developed based on the identified parameters and validated using internal validation.

Results: Pathological upgrading from mpMRI-TB to final RP specimens occurred in 38.8% (26/67) of the patients. Multivariable logistic regression analysis showed SUV (OR: 1.223, 95% CI 1.068-1.399, p = 0.003); highest tumor grade at mpMRI-TB, ISUP grade group (ISUP GG) 1 vs. 4 (OR: 0.11, 95% CI 0.000-0.452, p = 0.018) and ISUP GG 2 vs. 4 (OR: 0.16, 95% CI 0.001-0.252, p = 0.003); and multifocality on PET/CT (OR: 9.821, 95% CI 1.438-67.085, p = 0.02) were independent risk factors for pathological upgrading. Our developed prediction model based on the identified parameter showed good calibration at internal validation (mean absolute error = 0.033).

Conclusion: Ga-PSMA-11 PET/CT was found to be an ideal biomarker for the prediction of pathological upgrading from mpMRI-TB to RP, especially for patients with lower tumor grade at mpMRI-TB.