Can MRI/TRUS fusion targeted biopsy replace saturation prostate biopsy in the re-evaluation of men in active surveillance?

PURPOSE: The detection rate for significant prostate cancer of mMRI/TRUS fusion targeted biopsy versus saturation prostate biopsy was prospectively evaluated in men enrolled in active surveillance (AS) protocol.
METHODS: From May 2013 to January 2015, 40 men aged 66 years (median) with very low-risk PCa were enrolled in an AS protocol, and eligible criteria were: life expectancy greater than 10 years, cT1C, PSA below 10 ng/ml, PSA density <0.20, ≤2 unilateral positive biopsy cores, Gleason score (GS) equal to 6, greatest percentage of cancer (GPC) in a core ≤50 %. All patients underwent 3.0-Tesla pelvic mpMRI before confirmatory transperineal saturation biopsy (SPBx; median 30 cores) combined with mpMRI/TRUS fusion targeted biopsy (median 4 cores) of suspicious lesions (PI-RADS 4-5).
RESULTS: Ten out of 40 (25 %) patients were reclassified by SPBx based on upgraded GS ≥ 7; mpMRI found all the lesions predictive of significant PCa showing a false-positive rate equal to 5 %; on the contrary, mpMRI/TRUS targeted biopsy missed 3/10 (30 %) significant PCa characterised by the presence of a single positive core of GS ≥ 7 and GPC ≤ 5 %, suggesting that reduced number of targeted biopsies could miss small but significant PCa. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive value of mpMRI in diagnosing significant PCa were 95.2, 100, 93.8, 83.4, 100 %, respectively.
CONCLUSIONS: Although mpMRI provided high diagnostic accuracy (about 95 %) in diagnosing clinically significant PCa, mpMRI/TRUS fusion targeted biopsy cannot replace SPBx at confirmatory biopsy of men enrolled in AS protocols.