Abstract: PD56-05
Sources of Funding: This research was made possible through the NIH Medical Research Scholars Program, a public-private partnership supported jointly by the NIH and generous contributions to the Foundation for the NIH by the Doris Duke Charitable Foundation (Grant #2014194), the American Association for Dental Research, the Colgate-Palmolive Company, Genentech, and other private donors. For a complete list, visit the foundation website at http://www.fnih.org.

Introduction

Several studies have demonstrated the risk of upgrade from prostate biopsy (PBx) to radical prostatectomy (RP) pathology to be as high as 40%. The objective of the current study is twofold: to evaluate the prostate cancer upgrading on RP in a cohort of patients who underwent MRI-TRUS fusion biopsy (FBx) prior to RP and to determine if saturation of index tumor (IT) during PBx decreases this risk of upgrading.

Methods

Clinical and pathologic data from a prospectively maintained single institution database was analyzed for patients who underwent both FBx and standard 12-core biopsy (Sbx) followed by RP (2010-16). Index tumor was defined as the tumor with the largest diameter on T2W MRI. Patients were considered to have a saturated index tumor (SIT) if they had a fusion target (consisting of one axial and one sagittal biopsy) taken for every 6mm of IT diameter, and were considered to have a nonsaturated index tumor (NSIT) if they had only one target assigned regardless of the size of IT. Gleason 6, Gleason 7 and Gleason 8 or above were defined as low, intermediate and high risk respectively. Gleason Upgrade was defined as a higher Gleason score on RP specimen compared to PBx. Risk category upgrade was defined as higher risk category on RP specimen. Chi square and McNemar&[prime]s test were used to compare rates of upgrade.

Results

206 patients (91 with SIT and 115 with NSIT) were included in the study with median age and PSA of 61.5 (IQR 9.3) yrs and 7.38 (IQR 8) ng/ml respectively. Median number of biopsy cores per index tumor was 4 in the SIT group and 2 in the NSIT group (p<0.001) . For the entire cohort, highest Gleason score from combined Fbx/Sbx was upgraded on final pathology in 36 (17.5%) patients vs 95 (46.1%)patients when compared to Sbx only (p=0.001). Risk category upgrade from combined Fbx/Sbx vs Sbx only was found in 26 (12.6%) vs 83 (40.3%), p<0.0001. Patients with SIT had lower Gleason upgrade (12.1% vs 21.7% , p =0.07) and significantly lower risk category upgrade (6 (6.6%) and 20 (17.4%), p=0.02) compared to patients with NSIT.

Conclusions

Ensuring that high risk cancer is not missed on biopsy is crucial to treatment planning in patients with prostate cancer. Our results demonstrate that the addition of mpMRI-TRUS Fbx significantly decreases the risk of upgrade on RP pathology, proving the efficacy of Fbx in accurately characterizing PCa preoperatively. Saturation of the index tumor further decreases the risk of upgrade on final pathology by extensive sampling and minimizing the impact of tumor heterogeneity.

Funding

This research was made possible through the NIH Medical Research Scholars Program, a public-private partnership supported jointly by the NIH and generous contributions to the Foundation for the NIH by the Doris Duke Charitable Foundation (Grant #2014194), the American Association for Dental Research, the Colgate-Palmolive Company, Genentech, and other private donors. For a complete list, visit the foundation website at http://www.fnih.org.