Addition of MRI or DRE to clinical data and risk prediction for clinically significant prostate cancer.

e17105 Background: In patients suspected of prostate cancer, the decision to perform a biopsy hinges on available clinical data. Magnetic resonance imaging (MRI) and digital rectal exam (DRE) data are informative but may not be available. We created accurate models for clinically significant prostate cancer (csPCa), flexible to MRI and DRE data availability. Methods: Optimized ensembles of calibrated random forest models predicting csPCa (Grade Group ≥2) used total PSA, free PSA, prior negative biopsy status, and age, with or without DRE and MRI data (prostate volume and PI-RADS score). Risk models were derived (training cohorts n=1257 to 2191) and validated (validation cohorts n=317 to 1257) from different clinical sites. Models were evaluated by the area under the receiver operating characteristic curve (ROC AUC), sensitivity, specificity, positive predictive value, and negative predictive value, using thresholds providing ~ 95% sensitivity. Feature importance was determined by SHAP analysis. Results: All models had an AUC of at least 0.80, showing that predicting csPCa can be accurate without MRI or DRE data. Including MRI data significantly increased the AUC in the validation cohort (ClarityDX Prostate 0.80 vs ClarityDX Prostate +MRI 0.87). DRE had moderate value for models without MRI data (ClarityDX Prostate 0.80 vs ClarityDX Prostate +DRE 0.82) and minor value with MRI data (ClarityDX Prostate +MRI vs ClarityDX Prostate +DRE+MRI; AUC 0.87 vs 0.87; specificity 45% vs 47%, Table). Mean absolute SHAP values were highest for PI-RADS and prostate volume. Conclusions: These optimized risk models provide high accuracy for predicting csPCa in various clinical settings. Including MRI data greatly increases model accuracy, while DRE has a smaller effect on model accuracy. [Table: see text]