What is more accurate in detecting prostate cancer, PI-RADS (Prostate Imaging-Reporting and Data System) or SelectMDx?

PI-RADS is More Accurate Than SelectMDx for Detecting Prostate Cancer

PI-RADS v2 is more accurate than SelectMDx for detecting prostate cancer, with higher sensitivity (89-95%) and established clinical validation across multiple studies. 1

Diagnostic Performance of PI-RADS

Sensitivity and Specificity

• PI-RADS v2 demonstrates high sensitivity of 89% (95% CI 86-92%) with specificity of 73% (95% CI 60-83%) for prostate cancer detection 1
• In meta-analyses comparing PI-RADS versions, v2 showed even higher pooled sensitivity of 95% (95% CI 85-98%) 1
• The probability of cancer detection increases incrementally with PI-RADS v2 category: 16%, 33%, 71%, and 91% for PI-RADS 2,3,4, and 5 lesions, respectively 1

Clinical Validation

• PI-RADS is recommended by the European Association of Urology as a standardized scoring system to improve detection of clinically significant prostate cancers 2
• PI-RADS v2 has been extensively validated in multiple high-quality studies with whole-mount histopathology correlation 1
• The system has demonstrated consistent performance across different patient populations (biopsy-naïve, prior negative biopsy, active surveillance cohorts) 1

SelectMDx Performance

Sensitivity and Specificity

• SelectMDx shows variable sensitivity (81-87%) and specificity (63-74%) for prostate cancer detection across studies 3, 4
• For clinically significant prostate cancer, SelectMDx demonstrates 87.1% sensitivity but lower specificity (63.7%) compared to PI-RADS (83.9%) 3

Correlation with PI-RADS

• There is a positive association between SelectMDx score and PI-RADS grade, suggesting SelectMDx may be complementary rather than superior 5
• SelectMDx scores are significantly higher in patients with suspicious lesions on mpMRI compared to those without suspicious findings 5

Comparative Performance

Head-to-Head Comparison

• In direct comparisons, PI-RADS and SelectMDx show comparable sensitivity for prostate cancer detection (80.8% vs. 81%), but PI-RADS demonstrates better specificity (73.4% vs. 69.8%) 4
• For clinically significant prostate cancer, PI-RADS shows better specificity (83.9% vs. 63.7%) despite lower sensitivity (61.3% vs. 87.1%) 3

Combined Approach

• Some studies suggest a combined approach may be optimal, using SelectMDx as a triage test after negative mpMRI to identify patients who might still benefit from biopsy 3
• Combining SelectMDx with PI-RADS scores into a novel scoring system has shown promising results with AUC of 0.84 for prostate cancer detection 6

Clinical Implementation Considerations

PI-RADS Advantages

• PI-RADS is designed for standardized acquisition, interpretation, and reporting of prostate mpMRI, reducing inter-reader variability 2
• The European Urology guidelines recommend using PI-RADS assessment to guide biopsy decisions: no biopsy for PI-RADS 1-2, consider biopsy for PI-RADS 3, and MRI-directed plus systematic biopsy for PI-RADS 4-5 2

Limitations and Pitfalls

• PI-RADS performance is influenced by multiple factors including radiologist expertise, technical parameters, and the definition of clinically significant disease 1
• SelectMDx may miss some clinically significant cancers and has less extensive validation compared to PI-RADS 4
• Neither test is perfect - PI-RADS fails to detect all cancers but does identify the majority of clinically significant tumors 1

Practical Algorithm for Clinical Use

1. For initial prostate cancer detection, use PI-RADS as the primary diagnostic tool 2
2. Follow PI-RADS-based recommendations for biopsy decisions based on assessment category 2
3. Consider SelectMDx as a complementary test in specific scenarios:
   • After negative mpMRI to identify patients who might still benefit from biopsy 3
   • For PI-RADS 3 lesions to refine biopsy decisions 4