The role of multiparametric magnetic resonance in active surveillance of a low-risk prostate cancer cohort from clinical practice.

INTRODUCTION: Active surveillance (AS) is considered a suitable management practice for those patients with low-risk prostate cancer (PCa). At present, however, the role of multiparametric magnetic resonance imaging (mpMRI) in AS protocols has not yet been clearly established.

OUTCOMES: To determine the role of mpMRI and its ability to detect significant prostate cancer (SigPCa) in PCa patients enrolled in AS protocols.

MATERIALS AND METHODS: There were 229 patients enrolled in an AS protocol between 2011 and 2020 at Reina Sofía University Hospital. MRI interpretation was based on PIRADS v.1 or v.2/2.1 classification. Demographics, clinical, and analytical data were collected and analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for mpMRI in different scenarios. We defined SigPCa and reclassification/progression as a Gleason score (GS) ≥ 3 + 4, a clinical stage ≥T2b, or an increase in PCa volume. Kaplan-Meier and log-rank tests were used to estimate progression-free survival time.

RESULTS: Median age was 69.02 (±7.73) at diagnosis, with a 0.15 (±0.08) PSA density (PSAD). Eighty-six patients were reclassified after confirmatory biopsy, with a suspicious mpMRI an indication for a clear reclassification and risk-predictor factor in disease progression (p < 0.05). During follow-up, 46 patients were changed from AS to active treatment mainly due to disease progression. Ninety patients underwent ≥2mpMRI during follow-up, with a median follow-up of 29 (15-49) months. Thirty-four patients had a baseline suspicious mpMRI (at diagnostic or confirmatory biopsy): 14 patients with a PIRADS 3 and 20 patients with ≥PIRADS 4. From 14 patients with a PIRADS 3 baseline mpMRI, 29% progressed radiologically, with a 50% progression rate versus 10% (1/10 patients) for those with similar or decreased mpMRI risk. Of the 56 patients with a non-suspicious baseline mpMRI (PIRADS < 2), 14 patients (25%) had an increased degree of radiological suspicion, with a detection rate of SigPCa of 29%. The mpMRI NPV during follow-up was 0.91.

CONCLUSION: A suspicious mpMRI increases the reclassification and disease progression risk during follow-up and plays an important role in monitoring biopsies. In addition, a high NPV at mpMRI follow-up can help to decrease the need to monitor biopsies during AS.