Detection of prostate cancer by magnetic resonance imaging before biopsy – real-world evidence from a nationwide cohort study

OBJECTIVE: Magnetic resonance imaging (MRI) improves prostate cancer detection, but some tumours may be undetectable. This study assessed prostate cancer detection in biopsy-naïve men undergoing first-time prostate MRI. MATERIAL AND METHODS: In this nationwide Danish cohort (2018-2022), men aged ≥ 40 years undergoing first-time prostate MRI were classified as MRI-positive if biopsied within 30 days, and MRI-negative if not. This served as a proxy for the radiology report findings. One-year cumulative incidence of prostate cancer diagnosis in the Danish Prostate Cancer Registry, repeated MRI, biopsy and mortality was estimated by MRI-status (positive/negative) and prostate-specific antigen (PSA) level, using the Aalen-Johansen estimator. Occurrence of high-grade cancer was also assessed. RESULTS: Among 10,777 men, 40% were MRI-positive and 60% MRI-negative. The cumulative incidence of prostate cancer was higher in the MRI-positive than the MRI-negative men during 1-year follow-up (63% vs. 5% at PSA levels 2-3.9 µg/L), increasing with higher PSA levels (91% vs. 38% at PSA levels ≥ 20 µg/L). At 1 year, repeated MRI occurred in 21% of MRI-positive men and 9% of MRI-negative men; the subsequent 1-year biopsy incidence was 15% among MRI-negative men. Mortality was comparable between MRI-positive and MRI-negative men (1% vs. 1%). The risk of high-grade prostate cancer at the time of diagnosis was 80% in MRI-positive and 74% in the MRI-negative men. CONCLUSIONS: Among biopsy-naïve men undergoing first-time prostate MRI, MRI-positive status strongly predicts prostate cancer, even in men with low PSA. In MRI-negative men with PSA < 4.0 µg/L, prostate cancer risk remains low within the 2-year follow-up.