Utility of serial MRI/ultrasound fusion targeted biopsy in men with low risk prostate cancer managed with active surveillance
The utility of serial magnetic resonance imaging (MRI)/ultrasound (US) fusion targeted prostate biopsy in men with prostate cancer (PCa) on active surveillance (AS) have not been clearly defined. We sought to investigate the rate of Gleason upgrading both on sequential fusion targeted and systematic biopsies among men with very low risk and low risk PCa managed with AS.
We retrospectively queried an institutional database of 840 patients undergoing MRI/US fusion biopsy to identify 249 patients on AS with at least two fusion biopsies between December 2013 and November 2016. Men with National Comprehensive Cancer Network (NCCN) very low risk and low risk criteria were included. Gleason upgrade was defined as detection of Gleason score greater than or equal to 3+4. The proportion of patients experiencing upgrade on systematic, fusion, or both biopsy techniques was tabulated. Associations of clinical, pathological, and imaging factors with biopsy upgrade were analyzed by logistic regression.
Of 249 patients on active surveillance, 92 (37.0%) had at least two MR/US fusion guided biopsies (66% very low risk and 34% low risk PCa). The median time between biopsies was 13.0 months (IQR 11.6 to 17.4). The median PSA and PSA density were 5.5 ng/mL (IQR 4.3 to 7.2) and 0.12 ng/mL/mL (IQR 0.08 to 0.18), respectively. 27 (29%) patients experienced Gleason upgrade on subsequent MR-guided biopsy. Of those, 8 (9%), 9 (10%), and 10 (11%) had upgrade on systematic biopsy only, fusion biopsy only, and both systematic and fusion biopsy, respectively. Patients who upgraded on subsequent biopsy had higher PSA (p=0.02) and PSA density (p=0.02). Neither baseline PIRADS score nor change in lesion size was associated with Gleason upgrade. In multivariable logistic regression model, greater proportion of positive cores in systematic biopsy (OR 1.82; 95% CI 1.23 to 2.68; p=0.002) was associated with the total Gleason upgrade on repeated biopsy.
In men with favorable risk prostate cancer managed with AS, Gleason upgrade was detected in 29% of patients on a second MRI/US fusion biopsy including both targeted and systematic regions. Both MRI/ultrasound fusion targeted biopsy and systematic biopsy detected Gleason upgrade in a subset of patients that would have been missed if either technique were performed alone. These findings support the continued use of both MRI fusion targeted and systematic biopsy during surveillance due to risks of reclassification over time.