Abstract
ObjectivesTo assess the ability of multiparametric MRI (mp-MRI) of the prostate to exclude prostate cancer (PCa) progression during monitoring patients on active surveillance (AS).MethodsOne hundred forty-seven consecutive patients on AS with mp-MRI (T2WI, DWI, DCE-MRI) at 3T were initially enrolled. Fifty-five received follow-up mp-MRI after a minimum interval of 12 months and subsequent targeted MR/US fusion-guided biopsy (FUS-GB) plus concurrent systematic transrectal ultrasound-guided (TRUS-GB) biopsy as reference standard. Primary endpoint was the negative predictive value (NPV) of the follow-up mp-MRI to exclude histopathologic tumor progression using PRECISE recommendations. Secondary endpoints were the positive predictive value (PPV), sensitivity, specificity, Gleason score (GS) upgrades, and comparison of biopsy method.ResultsOf 55 patients, 29 (53%) had a GS upgrade on re-biopsy. All 29 patients showed a tumor progression on follow-up mp-MRI. Fifteen of 55 patients (27%) displayed signs of tumor progression, but had stable GS on re-biopsy. None of the 11 patients (20%) without signs of progression on follow-up mp-MRI had a GS upgrade on re-biopsy. The NPV was 100%, PPV was 66%, sensitivity was 100%, and specificity 42%. FUS-GB resulted in GS upgrade significantly more often (n = 28; 51%) compared with TRUS-GB (n = 12; 22%; p < 0.001).Conclusions(Follow-up) Mp-MRI can reliably exclude PCa progression in patients on AS. Standard serial re-biopsies might be waived if follow-up mp-MRIs are stable. Over 60% of patients with signs of tumor progression on mp-MRI during AS had a GS upgrade on re-biopsy. Targeted re-biopsies should be performed if cancer progression or higher-grade PCa is suspected on mp-MRI.Key Points• None of the patients with unsuspicious mp-MRI had a GS upgrade in re-biopsy and mp-MRI might replace serial biopsies in these cases• More than 60% of patients with mp-MRI signs of tumor progression had subsequent Gleason score (GS) upgrades• Targeted re-biopsies should be performed in case of higher GS cancer suspicion on mp-MRI
Highlights
Active surveillance (AS) is an increasingly applied therapy option for patients with low-risk prostate cancer (PCa) [1] to avoid overtreatment and spare men with presumably indolent disease potential complications and long-term effects [2]
The reason for histological reclassification in repeat biopsies is mainly the high rate of falsely too low Gleason score (GS) results in up to 50% of the cases in initial extended systematic transrectal ultrasound-guided biopsies (TRUS-GB), which used to be the standard method for selection of men eligible for AS and for monitoring [7,8,9]
Multiparametric magnetic resonance imaging and targeted MRI/US fusion-guided biopsy (FUS-GB) have been shown to substantially improve inclusion of patients in AS as they reduce the number of men with incorrectly diagnosed low-risk cancer that harbor clinically significant disease [10, 11]
Summary
Active surveillance (AS) is an increasingly applied therapy option for patients with low-risk prostate cancer (PCa) [1] to avoid overtreatment and spare men with presumably indolent disease potential complications and long-term effects [2]. According to current urological guidelines, monitoring of patients on AS is mainly based on serial prostate-specific antigen (PSA) testing and regular re-biopsies [3, 4] which might reveal histopathological tumor progression and induce definitive therapy, if needed. The reason for histological reclassification in repeat biopsies is mainly the high rate of falsely too low Gleason score (GS) results in up to 50% of the cases in initial extended systematic transrectal ultrasound-guided biopsies (TRUS-GB), which used to be the standard method for selection of men eligible for AS and for monitoring [7,8,9]. Multiparametric magnetic resonance imaging (mp-MRI) and targeted MRI/US fusion-guided biopsy (FUS-GB) have been shown to substantially improve inclusion of patients in AS as they reduce the number of men with incorrectly diagnosed low-risk cancer that harbor clinically significant disease [10, 11]. Results from the ASIST trial revealed that baseline mp-MRI before confirmatory biopsy can significantly decrease the number of AS failures and of tumor progression to higher-grade cancer after a 2-year follow-up episode [12, 13]
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