Purpose of review In men on active surveillance for localized prostate cancer, MRI and MRI-targeted biopsies can be used prior to confirmatory or surveillance biopsy, to detect individuals with high-grade cancer (the wolf in sheep's clothing). However, some men will have low-risk disease despite adverse MRI findings (the sheep in wolf's clothing). We review the value addition of MRI-targeted biopsies in comparison to systematic transrectal ultrasound-guided biopsies, using pathological reclassification as an end-point. Recent findings At confirmatory and surveillance biopsies, both the MRI-targeted and repeat standard biopsies have shown value in identifying histologically adverse findings in men with low-risk prostate cancer. For maximal detection of clinically significant cancer, a prebiopsy MRI should be performed together with both MRI-targeted and systematic transrectal ultrasound-guided biopsies. Stable disease on MRI may reduce the need for serial biopsies in some men on active surveillance. Summary Prostate MRI and subsequent MRI-targeted biopsies are worthwhile to the current management of men with low-risk prostate cancer on active surveillance. Prostate MRI, in combination with a multivariable risk-prediction model may help in identifying both the wolf in sheep's clothing and the sheep in wolf's clothing, and in potentially reducing the need for serial biopsies.

active surveillance, biopsies, monitoring, MRI, prostate cancer, risk prediction, systematic review
dx.doi.org/10.1097/MOU.0000000000000397, hdl.handle.net/1765/108501
Current Opinion in Urology
Department of Radiology

Schoots, I.G, Moore, C.M, & Rouvière, O. (2017). Role of MRI in low-risk prostate cancer: Finding the Wolf in sheep's clothing or the sheep in Wolf's clothing?. Current Opinion in Urology (Vol. 27, pp. 238–245). doi:10.1097/MOU.0000000000000397