MP43-07: Negative Prostate MRI as a Predictor of Disease Stability in Patients on Active Surveillance

Jacob Enders*, Michael Rothberg, Zach Kozel, Michael Daneshvar, Luke O'Connor, Alex Wang, Cheyenne Williams, Nitin Yerram, Sandeep Gurram, Maria Merino, Baris Turkbey, Bradford Wood, Peter Pinto, Bethesda, MD

Introduction: Active surveillance (AS) for prostate cancer (PCa) increasingly relies on regularly scheduled imaging with multiparametric MRI (mpMRI) and subsequent prostate biopsy. However, MRI scans are costly and time-consuming, and transrectal biopsies can cause significant patient morbidity due to infection. As such, patients may benefit from avoiding biopsy when the results are unlikely to change clinical management. We sought to identify patients in our AS cohort undergoing annual mpMRI and subsequent MRI-US fusion systematic and targeted biopsy who had no lesions detected on MRI and examine rates and risk factors for disease upgrading.

Methods: A prospectively maintained retrospective database of patients with biopsy-proven PCa on AS at our institution was queried to find patients with no distinct lesion on surveillance mpMRI who underwent subsequent MRI-US fusion biopsy from 2007 to 2019.  Patient demographics and information from prostate mpMRI and biopsy were collected, with clinically significant prostate cancer (csPCa) defined as Gleason grade group 2 or higher. A logistic regression model was constructed to examine risk factors for upgrading to csPCa at biopsy using JMP v16.0 (SAS Institute, NC).

Results: 466 patients on AS with at least one surveillance mpMRI were identified. Patients underwent an median of 4 MRIs across a median duration on AS of 3.4 years. The median age was 65.0 years (IQR: 60 – 69), median PSA was 5.4 ng/mL (IQR: 3.3 – 7.8), and median PSA density was 0.086 ng/mL/cc (IQR: 0.057 – 0.113). 120/466 (25.7%) patients had at least one surveillance mpMRI showing no distinct lesions in the prostate. Of these, 73/120 (60.8%) patients underwent at least one subsequent biopsy.  Across 95 biopsy sessions in these 73 patients, 33/95 (34.7%) showed equal-grade and 47/95 (49.5%) showed lower-grade cancers compared to previous pathology.  10/95 (10.5%) biopsies in 9/73 (12.4%) patients showed upgrading to csPCa. A multivariate logistic regression model showed increased PSA density was a significant predictor of upgrading to csPCa at biopsy (OR: 4.2 for increase of 0.100 ng/mL/cc, 95% CI: 1.5-11.9, p<0.01).

Conclusions: Negative mpMRI while on AS for prostate cancer resulted in equal grading or downgrading in the vast majority of patients undergoing subsequent biopsy. Patients with a negative mpMRI were more likely to be upgraded to csPCa with increasing PSA density. Thus, patients with a negative mpMRI, especially in the setting of a low PSA density, may be able to defer biopsy given the low likelihood for disease upgrading.

Source of Funding: The National Institute of Health (NIH) Medical Research Scholars Program, Foundation for the NIH, NIH Intramural Research Program