Abstracts from the New England Section of the AUA 2020: A Virtual Experience

NE AUA 2020 Abstracts 41* The Prognostic Impact of a Negative Confirmatory Biopsy and mpMRI in Men on Active Surveillance for Prostate Cancer Keyan Salari, MD, Jeffrey Twum-Ampofo, MD , Andrew Gusev, MD, Joshua Caldwell, MD, Edouard Nicaise, BS, David Kuppermann, MD, Dimitar Zlatev, MD, Douglas Dahl, MD, Jason Efstathiou, MD, Phil, Michael Blute, MD, Anthony Zietman, MD, Adam Feldman, MD, MPH. Massachusetts General Hospital, Boston, MA Introduction: Active surveillance (AS) is increasingly used in managing low-risk and favorable intermediate-risk prostate cancer. To mitigate the risk of unsampled higher risk disease, most institutional AS protocols call for a multiparametric MRI of the prostate (mpMRI) and a confirmatory prostate biopsy within 12-18 months following initial diagnostic biopsy. Here, we investigate whether the results of confirmatory biopsy and mpMRI impact the outcomes of men on AS. Materials & Methods: We retrospectively reviewed our institutional database of men enrolled in AS between 1997-2019 who underwent a confirmatory biopsy within 18 months of diagnosis and ≥ 3 biopsies overall. Patients who progressed to treatment on the basis of their confirmatory biopsy were excluded. Biopsies containing prostate cancer were considered positive. Biopsies containing only benign prostatic tissue, prostatic intraepithelial neoplasia (PIN), or atypical small acinar proliferation (ASAP) were considered negative.API-RADS v2 score of 3 or higher was considered a positive mpMRI. The primary outcome was biopsy progression-free survival and secondary outcomes included grade- and volume-related biopsy progression-free survival, biochemical recurrence, and metastasis-free survival. Statistical analysis was conducted using the Kaplan-Meier method and Cox proportional hazards regression. Results: Out of 1268 patients in our cohort, 470 met inclusion criteria for this analysis, with a median follow up of 7.2 years. At diagnosis, median age was 63 years (IQR 58- 68) and median PSA was 4.9 ng/mL (IQR 3.7-6.5). The vast majority of patients had grade group 1 (99%) and clinical stage T1 (95%) disease. A total of 177 patients (38%) had a negative confirmatory biopsy. Of the 470 patients, 38% progressed to treatment, with biopsy (grade- or volume-based) progression the most common reason (87%). In univariate analysis, a negative confirmatory biopsy and a negative initial mpMRI were each significantly associated with improved biopsy progression-free survival, while age of diagnosis, involvement of > 20% of any core on diagnostic biopsy, and PSA density ≥ 0.15 were associated with greater risk of biopsy progression. In multivariate analysis, a negative confirmatory biopsy remained a significant predictor of grade-based (but not volume-based) biopsy progression-free survival (HR 0.54 [95%CI 0.31-0.95], P = 0.03), whereas mpMRI status was no longer a significant predictor. Neither confirmatory biopsy nor mpMRI status were associatedwith biochemical recurrence or metastasis-free survival. Conclusions: A negative confirmatory biopsy is associated with a significantly lower rate of subsequent grade reclassification and progression to treatment among men on AS. This may serve as a useful tool for prognostication and help determine the intensity of interval biopsies for men on AS. *Max K. Willscher Award Eligible Free Hand Transperineal Prostate Biopsy Offers Equivalent Cancer Detection and Improved Antibiotic Stewardship Compared to Transrectal Ultrasound-Guided Prostate Biopsy Christian Schaufler, BS , Ryan Daigle, BS, Carl K. Gjertson, MD, Peter C. Albertsen, MD, Benjamin T. Ristau, MD University of Connecticut School of Medicine, Farmington, CT Introduction: Transrectalultrasoundguidedprostatebiopsy(TRUS-B) is thegoldstandard for diagnosing prostate cancer. Due to the risk of infectious complications associated with TRUS-B, there has been increasing interest in transperineal prostate biopsy. We compared a prospectively collected cohort of freehand transperineal prostate biopsy (fTP-B) to an institutional cohort of TRUS-B patients. Differences in cancer detection and the amount of cancer within a given core were examined. Materials &Methods: Ahistorical cohort of patients who received TRUS-B from January 2017 to September 2018 (n = 170) was compared to a prospectively collected cohort of fTP-B patients (n = 101) from February 2019 through January 2020. TRUS-B patients underwent a 10 or 12 core biopsy and fTP-B patients underwent a 20-core biopsy.All TRUS-B patients were treated with prophylactic antibiotics while fTP-B patients received no prophylaxis. Biopsy core length and percent of total core were determined from the surgical pathology report. Positive cancer was defined as grade group 1 or higher, while clinically significant cancer was defined as grade group 2 or higher. Cancer detection rates were compared using chi-squared tests, and core length and percentage of core length were compared using student’s T tests. A p value of < 0.05 was considered statistically significant. Results: 271 patients were included (170 TRUS-B, 101 fTP-B). Men undergoing fTP-B were slightly older (Median 65.6y, IQR 59.9-79.6) than those undergoing TRUS-B (63y, IQR 58.0-69.0; p = .03). There were no significant differences in median prostate PSA before biopsy (TRUS-B 9.4 ng/mL, IQR 6.8-17.4 and fTP-B 9.4, IQR 6.7-13.4; p=0.82), PSA density (TRUS-B 0.36, IQR 0.16-0.38 and fTP-B 0.48, IQR 0.19-0.42, p = 0.27), or race (p = 0.52) between the cohorts. Clinically significant prostate cancer was more often diagnosed in men undergoing fTP-B (52/101, 51.5%) compared to TRUS-B (64/170, 37.6%; p = 0.01). This difference was attenuated when a 12-core template for fTP-B was derived from the original 20-core template (47/101, 46.5%; p = 0.15) Cancer core length was greater in TRUS-B (median 4.0mm, IQR 1.2-8.5) relative to fTP-B (median 2.8mm, IQR 1-6; p < .001). There was no difference between percentage core involvement with cancer between TRUS-B (median 40%, IQR 10-75) and fTP-B (median 30%, IQR 10-70, p = .06). There were no infections in the fTP-B group and 2 confirmed cases of UTI/sepsis in the TRUS-B group. Conclusions: A20 core fTP-B results in greater detection of clinically significant prostate cancer compared to 10-12 core TRUS-B. This difference was attenuated when biopsy techniques with similar core numbers were compared. Despite omission of antibiotics in all cases, there were no infections in the fTP-B group. While 2 cases of UTI/sepsis were confirmed in the TRUS-B group, accurate determination of the infection rate in TRUS-B was limited due to lack of adequate follow-up information. Further work in disseminating fTP-B should be explored since fTP-B offers at least equivalent cancer detection and enables superior antibiotic stewardship compared to TRUS-B. 40 19 Scientific Session IV: Oncology II