Is A Systematic Transrectal Ultrasound-Guided Biopsy Required When A Targeted Magnetic Resonance Imaging-Ultrasound Fusion Biopsy Is Performed?

Magnetic resonance imaging (MRI)-ultrasound fusion targeted biopsy (TB) is increasingly used to diagnose prostate cancer. When TB is used, it is common practice to also perform a transrectal ultrasound-guided systematic biopsy (SB). We hypothesize that a patient’s National Comprehensive Cancer Network (NCCN) risk-group would not significantly change with the omission of SB when TB is used. In this IRB-approved prospective study, 594 patients underwent SB and TB for any MRI-visible lesion for the diagnosis of prostate cancer. A single urologist performed TB with a robotic biopsy device according to a standard protocol. The biopsy device selected SB locations independent of TB locations, and TB lesions were hidden during SB. Tissue cores were sent for histopathologic evaluation, and biopsy results were used as the standard for assessment of the presence of cancer. The proportion of patients in the NCCN (v 4.2018) very low/low (VL/L)*, favorable-intermediate (FI), unfavorable intermediate (UI), and high/very-high (H/VH)* risk groups were determined for TB and TB+SB groups (*combined due to small numbers). The Kappa statistic (0 = no agreement, 1 = perfect agreement) was used to measure agreement in NCCN risk groups between TB and TB+SB. Four hundred and twenty-five patients with adequate information for NCCN risk-stratification were analyzed. As expected, ISUP Grade Group with TB tended to be higher than SB (p<0.0001). There was almost perfect agreement in NCCN risk-group using TB with or without SB (Table 1), weighted kappa=0.92 (95% CI = 0.0.88-0.96). Only 18 patients (4%) had a lower NCCN risk-group with the omission of SB. Specifically, 11 patients (2.6%) were VL/L as opposed to FI, 5 patients (1.2%) were VL/L as opposed to UI, no patients were FI as opposed to UI, and 2 patients (0.5%) were UI as opposed to H/VH. There were no instances where the percentage of positive cores led to a change in risk group. Based on these results, the number needed to undergo SB in order to prevent one underestimation of the risk group is 25 patients. In this large study, underestimation of the NCCN risk-group with the omission of SB was highly improbable (4%). In light of the very large number of patients needed to undergo SB to prevent one underestimation of risk-group (25 patients), routine use of SB for risk categorization should be considered carefully. Without personalized factors that increase the baseline risk of higher-grade disease or otherwise support the need for SB, we propose that TB alone be an accepted practice standard for prostate cancer treatment decision-making.Abstract 2603; Table 1NCCN Risk Group calculated using TB+SB versus TB alone. Weighted kappa=0.92 (95% CI = 0.0.88-0.96).TB+SB NCCN Risk Group n (%)TB Alone NCCN Risk Group n (%)VL/LFIUIH/VHTotalVL/L46 (10.82%)00046 (10.82%)FI11 (2.59%)11 (2.59%)0022 (5.18%)UI5 (1.18%)0217 (51.06%)0222 (52.24%)H/VH002 (0.47%)133 (31.29%)135 (31.76%)Total62 (14.59%)11 (2.59%)219 (51.53%)133 (31.29%)425 (100%) Open table in a new tab