Adding PSMA PET CT to nomogram predicting extraprostatic extension of prostate cancer.

Abstract

Introduction: Probability on extraprostatic extension of prostate cancer determines feasibility of a nervesparing radical prostatectomy. Multiple nomograms have been developed calculating probability of EPE. Research shows benefits of PSMA PET/CT scans concerning primary staging, but also suggest possible benefits concerning local staging. Can the maximal standardized uptake value (SUVmax) of the PSMA PET/CT improve predictions made by Santeon nomogram? Materials & methods: A retrospective database consisting of 1400 patients diagnosed with prostate cancer patients was used. Patients with pre-operatively PSMA PET/CT and MRI prostate were extracted and analysed. Results: 117 patients were included and 137 tumour positive sides were identified. EPE was present in 35% of sides and 53% of all cases were deemed T3 according to the MRI report. Multivariable regression analyses showed that SUVmax is a significant predictor combined with the MRI T stadium to predict extraprostatic extension (EPE) and improves the area under the curve. Discussion: Cohort and number of events is small, therefore not all predictors could be included due to high degrees of freedom. Predictors deemed significant in other studies are not significant in this cohort, possibly due to small cohort. As SUVmax is significant opposed to other predictors it possesses a certain predictive value. Cases with non-visible tumours on PSMA PET/CT were not excluded and could possibly lower true predictive performance of variables. Conclusion: The relation between SUVmax and EPE is significant and thus strongly suggests SUVmax could be valuable in predicting side-specific extraprostatic extension.