Presentation Authors: Nina Mikkilineni*, Vinson Wang, Gen Li, Sven Wenske, New York, NY
Introduction: The use of MRI assistance in the diagnosis and surveillance of men with prostate cancer has become increasingly more widespread. The aim of our study was to determine the rate of pathology upgrading in men when MRI-guided fusion biopsy (FBx) is used after regular systematic/template biopsy (TRUS Bx), and to determine factors predictive of upgrading.
Methods: We conducted a retrospective review of all patients who underwent FBx (targeted MRI lesion plus 12-core template biopsy) at our institution between 2015 and 2018. Only patients with previous diagnosis of atypical small acinar proliferation (ASAP) or on active surveillance for prostate cancer diagnosed and previously surveyed by TRUS Bx were included. Any patients with >3 years between regular and FBx were excluded. Patient demographic data included age, number of regular biopsies before FBx, PIRADS grading of MRI lesion, PSA immediately prior to FBx, and time interval between regular and MRI biopsy. Outcome was rate of upgrading between TRUS Bx and FBx. Upgrading was defined as increase in Gleason grade and/or new positive core in a different prostate region on FBx. Chi-square and logistic regression models were used to determine significance.
Results: 294 patients underwent FBx and 33 (11. 2%) met inclusion criteria. Average age was 65.9 (+/-5.98) years. Median number of biopsies was 1 (range 1-4). Median PIRADS score was 4.0 (range 2-5) and median PSA prior to MRI biopsy was 5.20 (range 1.39-34.52). Average time interval between regular and MRI biopsies was 12.31 +/- 7.34 months. 19 patients (57.6%) were upgraded on FBx, 11 (33.3%) downgraded, and 3 (9. 1%) with the same grading. Using MRI template biopsy alone, 16 patients (48.5%) were upgraded. When using MRI lesion biopsy only, 14 (42.4%) were upgraded. These differences in detection compared to combined MRI lesion plus template biopsy were not statistically significant (p=0.93 and 0.84, respectively). When comparing upgraded to downgraded patients, PIRADS score was significantly higher in the upgraded group (4.06 vs. 3.20, p =0.008). On multivariable analysis, there were no significant factors predictive of FBx upgrading.
Conclusions: Previously published literature has shown an upgrading rate of about 30% between first and subsequent prostate biopsy. However, with the use of MRI, over half of our patients had upgrading. Biopsy of the MRI lesion alone would have missed 26% of patients with upgrading, emphasizing that template biopsy is still warranted at the time of fusion biopsy. Further studies with larger cohorts are needed to validate to our results.