Are magnetic resonance imaging undetectable prostate tumours clinically significant? Results of histopathological analyses

Abstract Objective To investigate whether tumours at threshold values for detection on magnetic resonance imaging (MRI) represent clinically significant tumours or not, and therefore the utility of MRI in active surveillance (AS) protocols. Patients and methods A retrospective analysis of a single institution database was performed after Institutional Review Board approval. Between 2010 and 2013, 1633 patients underwent robot-assisted laparoscopic prostatectomy (RALP) at a single institution by a single surgeon. Of these, 1361 had complete clinical data and were included in analysis. Multivariate logistic regression was used to assess histopathological grade compared to tumour size whilst controlling for biopsy Gleason score, prostate-specific antigen level, body mass index, race, and age. Results Of 120 tumours 3 + 4) at RALP compared to larger tumours (3.3% vs 25.1%, P P P Conclusions Prostate tumours below the detection threshold for MRI (5 mm) most probably represent clinically insignificant tumours, which alone would not necessitate leaving AS in favour of more aggressive therapy. These findings point to a possible role of MRI in modern AS protocols.