A Multivariable Approach Using Magnetic Resonance Imaging to Avoid a Protocol-based Prostate Biopsy in Men on Active Surveillance for Prostate Cancer—Data from the International Multicenter Prospective PRIAS Study

Abstract

BackgroundThere is ongoing discussion whether a multivariable approach including magnetic resonance imaging (MRI) can safely prevent unnecessary protocol-advised repeat biopsy during active surveillance (AS). ObjectiveTo determine predictors for grade group (GG) reclassification in patients undergoing an MRI-informed prostate biopsy (MRI-Bx) during AS and to evaluate whether a confirmatory biopsy can be omitted in patients diagnosed with upfront MRI. Design, setting, and participantsThe Prostate cancer Research International: Active Surveillance (PRIAS) study is a multicenter prospective study of patients on AS (www.prias-project.org). We selected all patients undergoing MRI-Bx (targeted ± systematic biopsy) during AS. Outcome measurements and statistical analysisA time-dependent Cox regression analysis was used to determine the predictors of GG progression/reclassification in patients undergoing MRI-Bx. A sensitivity analysis and a multivariable logistic regression analysis were also performed. Results and limitationsA total of 1185 patients underwent 1488 MRI-Bx sessions. The time-dependent Cox regression analysis showed that age (per 10 yr, hazard ratio [HR] 0.84 [95% confidence interval {CI} 0.71–0.99]), MRI outcome (Prostate Imaging Reporting and Data System [PIRADS] 3 vs negative HR 2.46 [95% CI 1.56–3.88], PIRADS 4 vs negative HR 3.39 [95% CI 2.28–5.05], and PIRADS 5 vs negative HR 4.95 [95% CI 3.25–7.56]), prostate-specific antigen (PSA) density (per 0.1 ng/ml cm3, HR 1.20 [95% CI 1.12–1.30]), and percentage positive cores on the last systematic biopsy (per 10%, HR 1.16 [95% CI 1.10–1.23]) were significant predictors of GG reclassification. Of the patients with negative MRI and a PSA density of <0.15 ng/ml cm3 (n = 315), 3% were reclassified to GG ≥2 and 0.6% to GG ≥3. At the confirmatory biopsy, reclassification to GG ≥2 and ≥3 was observed in 23% and 7% of the patients diagnosed without upfront MRI and in 19% and 6% of the patients diagnosed with upfront MRI, respectively. The multivariable analysis showed no significant difference in upgrading at the confirmatory biopsy between patients diagnosed with or without upfront MRI. ConclusionsAge, MRI outcome, PSA density, and percentage positive cores are significant predictors of reclassification at an MRI-informed biopsy. Patients with negative MRI and a PSA density of <0.15 ng/ml cm3 can safely omit a protocol-based prostate biopsy, whereas in other patients, a multivariable approach is advised. Being diagnosed with upfront MRI appears not to significantly affect reclassification risk; hence, a confirmatory MRI-Bx cannot totally be omitted yet. Patient summaryA protocol-based prostate biopsy while on active surveillance can be omitted in patients with negative magnetic resonance imaging (MRI) and prostate-specific antigen density <0.15 ng/ml cm3. A confirmatory biopsy cannot simply be omitted in all patients diagnosed with upfront MRI.