Abstract

5016 Background: Prostate Specific Membrane Antigen Positron-Emission-Tomography (PSMA-PET) was introduced for prostate cancer staging in 2012. PSMA-PET reported by standardized PROMISE criteria delivers accurate staging with potential prognostic value. Here we assess the prognostic value of PSMA-PET including tumor volume in a large prostate cancer dataset with overall survival follow-up and compare it head-to-head to clinical risk scores. Methods: Prostate cancer patients, who underwent PSMA-PET between October 2014 and December 2019 at the Essen University Hospital, were analyzed retrospectively. We collected PSMA-PET stage using the molecular imaging TNM system (miTNM), tumor volume, SUVmean and overall survival follow-up. The dataset was split into development and validation cohorts (2:1). We created a visual and quantitative nomogram based on Cox regression models with LASSO penalty using the development cohort. Performance of nomograms in the validation cohort were measured using C-index and calibration plots. Head-to-head comparison to clinical risk scores for each staging group was examined using ROC-curves and C-index. Results: The cohort includes 1612 prostate cancer patients across all disease stages with 567 (35.2%) recorded deaths. PSMA-PET based predictors included into the quantitative PSMA-PET nomogram were locoregional lymph node metastases (miN2), distant metastases (miM1a, miM1b pattern, miM1c), tumor volume and tumor SUVmean (Table). The visual nomogram includes distant metastases and total tumor lesion count. Overall C-indices were 0.81 or 0.78 for the quantitative or visual nomogram, respectively. The quantitative PSMA-PET nomogram was superior to STARCAP at initial staging (AUC: 0.72 vs. 0.53; p=0.02), to EAU risk score at BCR (AUC: 0.69 vs. 0.52; p<0.001), and to NCCN groups at any timepoint (AUC: 0.81 vs. 0.73; p<0.001). The visual PSMA-PET nomogram was superior to EAU risk score (AUC: 0.64 vs. 0.52; p<0.001) and NCCN groups (AUC: 0.79 vs. 0.73 p<0.001). Conclusions: Our prognostic PSMA-PET nomograms based on PROMISE criteria were accurate in early and late stages of prostate cancer. Prediction of overall survival was superior when compared to clinical risk tools. Multi-center validation in the PROMISE registry is ongoing. Development cohort (n=1110 patients) univariate regression findings for PROMISE variables included in the quantitative PSMA-PET nomogram for prediction of overall survival.[Table: see text]