New England Section of the American Urological Association

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Impact of MRI-Ultrasound Fusion Prostate Biopsy On Pathologic Downgrading During Radical Prostatectomy
Jeannie J. Su, MD, Kamyar Ghabili Amirkhiz, MD, Sarah Amalraj, MD, Michael Leapman, MD, Preston Sprenkle, MD
Yale, New Haven, CT

BACKGROUND: The discordance between Gleason grade at systematic prostate biopsy and radical prostatectomy is well established. The integration of MRI-ultrasound fusion improves the detection of clinically significant prostate cancer, but it is unknown if this approach over- estimates risk by directly sampling tumors. Therefore, we aimed to evaluate the concordance of MR fusion biopsy approaches and radical prostatectomy (RP) pathology. METHODS: We conducted a retrospective review of an institutional database of men undergoing MRI/US fusion biopsy between February 2013 and March 2018. We compared Gleason grade group (GG) of systematic 12-core, MRI/US targeted, and combined biopsy approaches with whole gland prostatectomy pathology. We evaluated rates of downgrading in the entire cohort, and among subsets of intermediate and high-risk cancer. Binomial logistic regression was utilized to identify clinical, radiologic, and pathologic features associated with downgrading of combined MRI/US fusion prostate biopsy pathology on radical prostatectomy. RESULTS: We identified 192 men who underwent MRI/US fusion biopsy and were treated with RP. The overall rate of downgrading at RP was 33%, including 29% (n=55) based on Gleason grade from targeted biopsy, and 13% (25) from systematic biopsy (p<0.001). Among patients with GG3 on biopsy (46), 57% (26) were downgraded to GG2 prostate cancer on final prostatectomy pathology. There were higher rates of downgrading when regarding targeted biopsy (47%) compared to systematic biopsy (17%) (P=0.01). Among patients with GG4 and GG5 (47), 74% (35) were downgraded on final prostatectomy pathology. There were higher rates of downgrading when regarding targeted biopsy (68%) compared to systematic biopsy (34%) (P=0.001). On multivariable regression analysis adjusted for clinical, radiologic, and pathologic factors, targeted biopsy Gleason GG (GG3-5 vs. GG1) remained the only variable significantly associated with downgrading on final pathology (P<0.05). CONCLUSIONS:
Although MRI/US fusion biopsy improves detection of high grade cancer, a substantial proportion of patients were downgraded at radical prostatectomy. Further investigation is warranted to improve the concordance between biopsy and final pathology.


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