Introduction & objectives: Prostate cancer (PCa) diagnostics would greatly benefit from more accurate, non-invasive techniques for the detection of clinically significant disease, leading to a reduction of over-treatment. Multiparametric MRI (mpMRI) is being used increasingly and has proven to be a valuable addition in diagnostics. A novel biomarker-based risk score (SelectMDx) assessing urinary HOXC6 and DLX1 mRNA expression levels combined with traditional clinical risk factors, was recently developed to predict high-grade PCa (Gleason score ≥7) upon prostate biopsy and to reduce the number of unnecessary biopsies. The aim of this study was to investigate the association between this urinary biomarker-based risk score and mpMRI outcomes.
Material & methods: The patients in this retrospective observational cohort were previously included in the validation study of the SelectMDx risk score, in which urine was collected after digital rectal examination from men undergoing prostate biopsies. A subset of these patients underwent a mpMRI after prostate biopsies were performed. The indications for performing mpMRI were based on persistent clinical suspicion of PCa or local staging after PCa was found upon biopsy. All mpMRI images were centrally reviewed in 2016 by an experienced radiologist blinded for the urine test results and biopsy outcome.
Results: In total, 172 patients were included for analysis. Hundred (58%) patients had PCa detected upon prostate biopsy, of which 52 (52%) had high-grade disease correlated with a significantly higher SelectMDx score (p<0.01). The median SelectMDx score was significantly higher in patients with a suspicious significant lesion on mpMRI compared to no suspicion of significant PCa (p<0.01). For the prediction of mpMRI outcome, the area-under-the-curve of SelectMDx was 0.83 compared to 0.66 for PSA. There was a positive association between SelectMDx score and the final PI-RADS grade (Figure 1). Moreover, the differences in SelectMDx score between PI-RADS 3 and PI-RADS 4 (p<0.01) and between PI-RADS 4 and 5 (p<0.01) were statistically significant.
Conclusion: This study showed promising results regarding the correlation between the novel urinary biomarker-based SelectMDx score and mpMRI outcomes. Our results suggest that this risk score could guide clinicians in identifying patients at risk for significant PCa and selecting patients for further radiological diagnostics to reduce unnecessary procedures.
