Abstract
BACKGROUND: Although the use of multiparametric magnetic resonance imaging (mpMRI) in active surveillance (AS) for prostate cancer is of increasing interest, existing data are derived from small cohorts. OBJECTIVE: We describe clinical, histological, and radiological outcomes from an established AS programme, where protocol-based biopsies were omitted in favour of MRI-led monitoring. DESIGN, SETTING, AND PARTICIPANTS: Data on 672 men enrolled in AS between August 2004 and November 2017 (inclusion criteria: Gleason 3 + 3 or 3 + 4 localised prostate cancer, presenting prostate-specific antigen <20 ng/ml, and baseline mpMRI) were collected from the University College London Hospital (UCLH) database. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Primary outcomes were event-free survival (EFS; event defined as prostate cancer treatment, transition to watchful waiting, or death) and treatment-free survival (TFS). Secondary outcomes included rates of all-cause or prostate cancer-related mortality, metastasis, and upgrading to Gleason ≥4 + 3. Data on radiological and histological progression were also collected. RESULTS AND LIMITATIONS: More than 3800 person-years (py) of follow-up were accrued (median: 58 mo; interquartile range 37-82 mo). Approximately 84.7% (95% confidence interval [CI]: 82.0-87.6) and 71.8% (95% CI: 68.2-75.6) of patients remained on AS at 3 and 5 yr, respectively. EFS and TFS were lower in those with MRI-visible (Likert 4-5) disease or secondary Gleason pattern 4 at baseline (log-rank test; p < 0.001). In total, 216 men were treated. There were 24 deaths, none of which was prostate cancer related (6.3/1000 py; 95% CI: 4.1-9.5). Metastases developed in eight men (2.1 events/1000 py; 95% CI: 1.0-4.3), whereas 27 men upgraded to Gleason ≥4 + 3 on follow-up biopsy (7.7 events/1000 py; 95% CI: 5.2-11.3). CONCLUSIONS: The rates of discontinuation, mortality, and metastasis in MRI-led surveillance are comparable with those of standard AS. MRI-visible disease and/or secondary Gleason grade 4 at baseline are associated with a greater likelihood of moving to active treatment at 5 yr. Further research will concentrate on optimising imaging intervals according to baseline risk. PATIENT SUMMARY: In this report, we looked at the outcomes of magnetic resonance imaging (MRI)-based surveillance for prostate cancer in a UK cohort. We found that this strategy could allow routine biopsies to be avoided. Secondary Gleason pattern 4 and MRI visibility are associated with increased rates of treatment. We conclude that MRI-based surveillance should be considered for the monitoring of small prostate tumours.