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External Validation of MRI-Based Prostate Cancer Risk Calculators in a Contemporary Pre-Biopsy mpMRI Cohort

Year: 2026

Type: article

Abstract: Background: MpMRI-integrated risk calculators have been developed to improve individualized prediction of clinically significant prostate cancer (csPCa) before biopsy. Although these models have demonstrated good predictive performance in previous validation studies, their performance and clinical utility may vary across patient populations and diagnostic pathways. This study externally validated the mpMRI-based prostate cancer risk calculators developed by Radtke et al. (Radtke-RC) and Alberts et al. (Alberts-RC) in a contemporary pre-biopsy mpMRI population and directly compared both models within the same patient population. Methods: We retrospectively included patients undergoing pre-biopsy mpMRI followed by combined MRI-targeted and systematic prostate biopsy. Predicted probabilities of clinically significant prostate cancer (csPCa; ISUP Grade Group ≥ 2) were calculated using the Radtke and Alberts MRI-integrated risk calculators. Discrimination was assessed using receiver operating characteristic analysis and compared using DeLong’s test. Clinical utility was evaluated using decision curve analysis across a range of threshold probabilities, with thresholds of 12%, 20%, and 30% used for descriptive interpretation of net benefit and potential reductions in unnecessary biopsies. Results: Of 171 screened patients, 164 were eligible for validation of the Radtke-RC, including 62 (37.8%) with csPCa. Complete data for both calculators were available in 114 patients, of whom 41 (36.0%) had csPCa. In the head-to-head cohort, discrimination was acceptable for both calculators (AUC 0.785 for Radtke-RC vs. 0.767 for Alberts-RC; DeLong p=0.318). Decision curve analysis demonstrated threshold-dependent clinical utility. The Radtke-RC provided greater net benefit than biopsy-all from approximately 9% to 69%, whereas the Alberts-RC provided greater net benefit from approximately 18% to 56%. At 12%, incremental benefit over biopsy-all was marginal for the Radtke-RC and absent for the Alberts-RC. At 20%, the Radtke-RC and Alberts-RC reduced unnecessary biopsies by 7.9 and 4.4 per 100 patients, respectively, corresponding to numbers needed to assess of approximately 13 and 23 to avoid one unnecessary biopsy. At 30%, the corresponding reductions were 12.9 and 10.8 per 100 patients, with numbers needed to assess of approximately 8 and 9, respectively. Conclusions: Both the Radtke and Alberts MRI-integrated risk calculators demonstrated acceptable and comparable discrimination for csPCa, with neither model showing a clear overall advantage. Clinical utility was strongly threshold-dependent, with limited incremental benefit over biopsy-all at low thresholds but increasing potential to reduce unnecessary biopsies at higher thresholds. These findings suggest that the principal value of MRI-integrated risk calculators in an already MRI-selected population lies in supporting individualized biopsy decisions. Threshold selection should therefore reflect the clinical trade-off between avoiding unnecessary biopsy and minimizing missed csPCa. Further prospective multicentre validation is warranted to define clinically appropriate thresholds.

Source: Journal of Clinical Medicine

DOI: 10.3390/jcm15208146