Abstracts from the New England Section of the AUA 2021

NE-AUA 2021 Abstracts Concurrent Scientific Session IV: Oncology II 36 Limitations ofMultiparametricMagnetic Resonance Imaging for Detection of Extraprostatic Extension in Prostate Cancer: Implications for Nerve Sparing Approaches Stephen Schmit, BS 1 , Rebecca Ortiz, BA 2 , Randall Li, MD 1 , SiddharthMarthi, BA 1 , Ji Whae Choi, BA 1 , KathleenWu, BA 1 , Philip Caffery, PhD 2 , Christopher Tucci, MS 1 , Mohammad Hout, MD 1 , DavidW. Sobel, MD 1 , Dragan Golijanin, MD 1 , Gyan Pareek, MD 1 , Elias Hyams, MD 1 1 Minimally Invasive Urology Institute, The Miriam Hospital; The Warren Alpert Medical School of Brown University, Providence, RI, USA; 2 Minimally Invasive Urology Institute, The Miriam Hospital, Providence, RI, USA Introduction: Multiparametric magnetic resonance imaging (MRI) is increasingly used for pre-operative staging of prostate cancer as well as for surgical planning. Concern for extraprostatic extension (EPE) onMRI suggests that wider dissection (inter-, extra-fascial, or non-nerve sparing approaches) may be warranted. It is not clear how MRI findings and Grade Group (GG) interact to determine the presence of EPE on surgical pathology. Materials & Methods: A retrospective review of a robotic assisted laparoscopic radical prostatectomy (RALP) database from a single academic institution from 2016-2020 was performed. MRI reports were assessed for positive or possible EPE findings to determine the sensitivity and negative predictive value (NPV) for pathological EPE. The data was further stratified by GG to determine the relationship between tumor grade andMRI findings. Results: A total of 173 patients underwent at least one MRI prior to RALP. 106/173 (61%) patients had GG 3-5 tumors, 59/173 (34%) had GG 4-5 tumors, and 45/173 (26%) had GG 5 tumors. The overall sensitivity of MRI for pathological EPE was 37.6%, and stratification by GG yielded the following sensitivities: GG 3-5, 40.6%; GG4-5, 50.8%; GG 5, 53.3%. The overall NPV was 50.2%, and stratification revealed the following NPVs: GG 3-5, 31.6% ; GG 4-5, 16.2%; GG 5, 12%. Conclusions: The sensitivity of MRI for EPE improved with higher grade prostate tumors, but remained relatively low evenwith GG 5 tumors. NPV for EPE was low and decreased further with higher grade tumors. This suggests caution in aggressive nerve sparing approaches with higher grade tumors even in the setting of a reassuring MRI. PRState: Incorporating Genetic Ancestry in Prostate Cancer Risk Scores for Men of African Descent Joshua A. Linscott, MD, PhD 1 , Meghana S. Pagadala, BS 2 , Hannah Carter, PhD 2 , Matthew H. Hayn, MD 1 , Moritz H. Hansen, MD 1 , Jesse D. Sammon, DO 1 , Karim Kader, MD, PhD 3 , Stephen T. Ryan, MD 1 1 Maine Medical Center, Portland, ME, USA; 2 UCSD School of Medicine, San Diego, CA, USA; 3 UCSD Department of Urology, San Diego, CA, USA Introduction: Prostate cancer (PrCa) is the most heritable of the solid organ malignancies. In addition, incidence and aggressive phenotypes are higher in AfricanAmericanmen. Prior research into genetic heritability has focused on ancestry as defined by the patient. We explored ancestral genetic backgrounds with forensic genetic tools to define and develop a polygenic risk score (PRS) in African Americans. Materials & Methods: Single nucleotide polymorphisms (SNPs) were imputed from a PrCa case-control study of >99,000 men (ELLIPSE) using the Michigan Imputation Server, 1000 Genomes Project, Eaglev2.3. Ancestral likelihood ratios were calculated by Forensic Research Reference on Genetics (FROG)-kb based on a previously described 55-SNP panel and define genetically separate African and European cohorts. GWAS was performed to identify PrCa risk SNPs and PRSice 2.3.1 to develop a PRS. An 80:20 split training:testing groups was used with AUC and ROC analysis. Results: FROG-kb identified 4,507 and 5,334 individuals of African and European ancestry, respectively ( Figure 1 ). In theAfrican group, multiple loci reached significance on chromosome 1, 8, and 11. From this GWAS, 6 SNPs unique to African ancestry, were used to create a PRS. Individually, family history (FH), age, and PRS achievedAUCs of 0.56, 0.54, and 0.60 respectively. Combined PRS, FH, and Age improved AUC to 0.64 ( Figure 2 ). Conclusions: A55-SNP panel identified genetic ancestral groups for GWAS analysis, which defined 6 PrCa associated SNPs specific to African genetic inheritance. The resulting PRS predicted PrCa better than FH and Age in African American men. A combined model performs similar to previously published studies in European cohorts. Here we have achieved comparable AUC using only 6 SNPs, in a group at higher risk for aggressive PrCa. 35 19