How does a prebiopsy mri approach for prostate cancer diagnosis affect prostatectomy upgrade rates?

BACKGROUND

To compare the pathologic upgrade and downgrade rates after radical prostatectomy (RP) between patients diagnosed by prebiopsy prostate MRI followed by a combination of systematic and fusion biopsy (ComBx) versus patients undergoing systematic biopsy only (SBx).

METHODS

A retrospective review of men undergoing RP at our institution between Jan 2014 and Mar 2020 was performed. These patients were separated into two independent cohorts based on two approaches: Patients receiving prebiopsy prostate MRI during initial evaluation and those who did not receive MRI. Patients with positive MRI findings underwent subsequent ComBx to confirm diagnosis while those without MRI underwent standard trans-rectal ultrasound (TRUS) guided systematic 12-core biopsy (SBx). Primary outcomes were rates of pathological upgrade (prostatectomy grade higher than grade determined at time of biopsy) and downgrade (prostatectomy grade lower than biopsy grade).

RESULTS

A total of 213 patients undergoing radical prostatectomy, 91 diagnosed via a prebiopsy MRI and ComBx approach and 122 diagnosed by a traditional SBx approach, were included in the study. There was no significant difference between age, PSA, or positive family history between the two cohorts. Of the 91 patients who received prebiopsy MRI, 88 patients were determined to have a PIRADS 4 or 5 lesion. Patients who received MRI and subsequent ComBx had a lower rate of any pathological upgrade after RP (9.89% vs. 22.13%, P = 0.018) without a significant difference in pathologic downgrade rate (28.57% vs. 18.85%, P = 0.095). On multivariable logistic regression, receiving prebiopsy MRI during initial evaluation was the single negative independent predictor of pathologic upgrade (OR = 0.23, P = 0.017). A prebiopsy MRI approach was also the single predictor of pathologic downgrade (OR = 3.13, P = 0.041).

CONCLUSIONS

Patients receiving prebiopsy MRI during prostate cancer evaluation were less likely to have their PCa upgraded. Furthermore, although diagnosis via MRI and subsequent ComBx was associated with an increased rate of downgrades after RP, relatively few resulted in a downgrade from clinically significant to clinically insignificant cancer.