A noninferiority within-person study comparing the accuracy of transperineal to transrectal MRI-US fusion biopsy for prostate-cancer detection

Background Magnetic resonance imaging (MRI) and ultrasound (US) fusion prostate-biopsies can be performed in a transrectal (TR-fusion) or transperineal (TP-fusion) approach. Prospective comparative evidence is limited. In this study we compared the detection rate of clinically-significant prostate-cancer (csPCa) within an index lesion between TR and TP-fusion. Patients and methods This was a prospective, noninferiority, and within-person trial. Men scheduled for MRI-US-fusion with a discrete MRI PI-RRAD >= 3 lesion were included. A dominant index lesion was determined for each subject and sampled by TR and TP-fusion during the same session. The order of biopsies was randomized and equipment was reset to avoid chronological and incorporation bias. For each subject, the index lesion was sampled 4-6 times in each approach. All biopsies were performed using Navigo fusion software (UC-Care, Yokneam, Israel). csPCa was defined as: Grade Group >= 2 or cancer-core length >= 6 mm. We used a noninferiority margin of 10% and a one-sided alpha level of 5%. Results Seventy-seven patients completed the protocol. Median age was 68.2 years (IQR:64.2-72.2), median PSA was 8.9 ng/ml (IQR:6.18-12.2). Ten patients (13%) were biopsy naive, others (87%) had a previous biopsy. csPCa was detected in 32 patients (42%). All of these cases were detected by TP-fusion, while only 20 (26%) by TR-fusion. Absolute difference for csPCa diagnosis was 15.6 (CI 90% 27.9-3.2%) in favor of TP-fusion (p = 0.029). TP-fusion was noninferior to TR-fusion. The lower boundary of the 90% confidence-interval between TP-fusion and TR-fusion was greater than zero, therefore TP-fusion was also found to be superior. Exploratory subgroup analyses showed TP-fusion was consistently associated with higher detection rates of csPCa compared with TR-fusion in patient and index-lesion derived subgroups (size, location, PI-RADS, PSA, and biopsy history). Conclusions In this study, TP-fusion biopsies were found to be noninferior and superior to TR-fusion biopsies in detecting csPCa within MRI-visible index lesion. Centers experienced in both TP and TR-fusion should consider these results when choosing biopsy method.