A Multicenter, Randomized Controlled Superiority Trial Comparing Robotic-Assisted Versus Expert Cognitive Fusion Prostate Biopsy in Abdominally Obese Men

The trial aims to find out if using a robotic system to help perform prostate biopsies is better than having a highly experienced doctor perform the biopsy by hand in men with a high Body Mass Index (BMI).

While MRI-guided prostate biopsies are highly effective, carrying them out in men with obesity can be physically challenging for doctors. Extra pelvic tissue increases the depth the biopsy needle must travel and makes it difficult to manually hold the ultrasound probe perfectly steady. This physical difficulty might cause doctors to miss some aggressive prostate cancers.

This study tests whether a robotic arm-which completely locks the biopsy needle on target and eliminates human hand tremors-can improve cancer detection. The study will enroll up to 570 men with high BMI who have suspicious areas on their prostate MRI. Participants will be randomly assigned to receive either a robotic-assisted biopsy or a standard manual biopsy performed by an expert urologist.

To ensure the results are completely unbiased, participants will not know which method is being used on them. They will be placed behind a surgical drape and wear noise-canceling headphones playing music during the procedure to block out the sounds of the robotic motors. The main goal is to see if the robotic method safely and significantly increases the detection rate of clinically significant prostate cancer in this specific group of patients.

Study Overview

• Status: Not yet recruiting
• Conditions: Prostate Biopsy
• Intervention / Treatment: Procedure: Robotic-Assisted Fusion Biopsy; Procedure: Expert Cognitive Fusion Biopsy

Detailed Description

The integration of multiparametric magnetic resonance imaging (mpMRI) with transperineal targeted biopsy has established a new standard for prostate cancer diagnosis. However, clinical evidence, including findings from the previous IMAGINATION trial, suggests that the diagnostic accuracy of manual targeted biopsy techniques degrades significantly in patients with high Body Mass Index (BMI).

Deep perineal adiposity creates a "hostile anatomical environment." It increases the skin-to-apex distance and introduces a "fulcrum effect," where the extensive soft tissue acts as a pivot point that amplifies manual tremors and restricts the operator's physical ability to steer the transperineal probe accurately. This mechanical barrier contributes to the "Obesity Paradox," wherein men with obesity face a higher risk of harboring undiagnosed, advanced high-grade prostate cancer.

The ROBUST (Robotic Optimization for Biopsy Under Substantial Tissue) trial is an investigator-initiated, international, multicenter, randomized controlled trial designed to determine if robotic stabilization can serve as a "technical equalizer" for this specific anatomical challenge.

Unlike conventional device trials, ROBUST utilizes a Bayesian adaptive hierarchical non-inferiority to superiority design. It aims to test whether robotic-assisted fusion biopsy is strictly non-inferior (with a -5% margin), and subsequently superior, to expert cognitive fusion biopsy. To rigorously isolate the impact of mechanical stabilization from operator inexperience, the control arm explicitly represents "peak human performance," mandating that human operators be credentialed experts with a documented history of >500 total prostate biopsies and >200 cognitive fusion targeted cases.

To eliminate performance bias and placebo effects on patient-reported outcomes (such as procedural anxiety and pain), the trial implements a strict single-blind (patient-blinded) protocol. A high surgical drape and noise-canceling headphones are utilized to completely mask the distinct motor operations of the robotic platform from the participant.

Furthermore, to mitigate the inherent recruitment fatigue associated with this highly specific demographic, the study incorporates a Bayesian sequential monitoring framework. An independent Data Safety Monitoring Board (DSMB) will evaluate Posterior Probability and Predictive Probability of Success (PPOS) at predefined interim looks (N=200, 300, and 400). This allows the trial to be halted early for either overwhelming efficacy or objective futility. By strictly targeting the "stress test" population, ROBUST seeks to provide Level 1 evidence for a risk-stratified precision diagnostic pathway, evaluating whether high-cost robotic technology is an absolute clinical necessity for men with obesity.

• Study Type: Interventional
• Enrollment (Estimated): 570
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Qiang Li; Phone Number: +8613801602220; Email: liqressh@hotmail.com
• Study Contact Backup: Name: haifeng wang; Phone Number: +8613681759891; Email: kuohaiandrew2000@vip.sina.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age ≥ 40 years.
• Serum PSA levels between 4 and 20 ng/ml and/or abnormal digital rectal examination (DRE).
• High Body Mass Index (BMI): defined as ≥ 28 kg/m ² for Asian cohorts and ≥ 30 kg/m ² for Non-Asian cohorts.
• MRI-Positive: Presence of at least one suspicious lesion (PI-RADS score ≥ 3) on mpMRI.
• Fitness for transperineal biopsy under local anaesthesia or conscious sedation.

Exclusion Criteria:

• Prior treatment for prostate cancer.
• History of major anorectal surgery preventing safe transperineal probe insertion.
• Contraindications to MRI.
• Negative screening MRI (PI-RADS 1-2).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Robotic-Assisted Fusion Biopsy	Procedure: Robotic-Assisted Fusion Biopsy; Participants in this arm will undergo a transperineal prostate biopsy utilizing a dedicated robotic fusion platform. The system features a mechanical arm or rigid fixator that completely locks the ultrasound probe and needle guide into a pre-planned coordinate trajectory. This mechanical stabilization uncouples the needle guide from manual human force, eliminating operator hand tremor and the "fulcrum effect" caused by deep pelvic adiposity. The urologist will obtain 3 to 4 targeted cores per MRI-visible lesion (PI-RADS ≥ 3) using the robotic interface, followed by a standard systematic biopsy. To prevent performance bias and placebo effects, participants will be blinded to the intervention using a high surgical drape and noise-canceling headphones.
Active Comparator: Expert Cognitive Fusion Biopsy	Procedure: Expert Cognitive Fusion Biopsy; Participants in this arm will undergo a standard manual transperineal prostate biopsy. To represent "peak human performance," the procedure will be performed exclusively by an expert urologist credentialed with a documented history of >500 total prostate biopsies, including >200 cognitive fusion targeted cases. The operator will mentally register the MRI lesion onto the real-time ultrasound image using anatomical landmarks, without the aid of any software overlay or robotic mechanical stabilization. The urologist will manually obtain 3 to 4 targeted cores per MRI-visible lesion (PI-RADS ≥ 3), followed by a standard systematic biopsy. To maintain the single-blind study design, participants will be shielded by a surgical drape and wear noise-canceling headphones.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Detection Rate of Clinically Significant Prostate Cancer (csPCa) by Targeted Biopsy	The primary efficacy endpoint is the proportion of participants in the intention-to-treat (ITT) population diagnosed with clinically significant prostate cancer (csPCa) specifically from the targeted biopsy cores. csPCa is strictly defined histopathologically as International Society of Urological Pathology (ISUP) Grade Group 2 or higher (Gleason score 3+4=7 or greater).	Up to 30 days post-procedure (at the time of final pathology report)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Detection Rate of Any Prostate Cancer by Targeted Biopsy	The proportion of participants in whom any prostate cancer, defined as ISUP Grade Group 1 or higher (Gleason score 3+3=6 or greater), is detected specifically from the targeted biopsy cores.	Up to 30 days post-procedure
Detection Rate of csPCa by Combined Biopsy	The proportion of participants diagnosed with clinically significant prostate cancer (ISUP Grade Group 2 or higher) when combining the pathological results from both the targeted biopsy cores and the standard systematic biopsy cores.	Up to 30 days post-procedure
Pathological Upgrade Rate	The proportion of participants in whom the targeted biopsy cores detect a higher ISUP Grade Group of prostate cancer compared to the ISUP Grade Group detected by the background systematic biopsy cores in the same patient.	Up to 30 days post-procedure

Collaborators and Investigators

• Sponsor: Shanghai East Hospital
• Investigators: Principal Investigator: haifeng wang, Shanghai East Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): May 30, 2026
• Primary Completion (Estimated): May 30, 2028
• Study Completion (Estimated): May 30, 2028

Study Registration Dates

• First Submitted: May 14, 2026
• First Submitted That Met QC Criteria: May 14, 2026
• First Posted (Actual): May 20, 2026

Study Record Updates

• Last Update Posted (Actual): May 20, 2026
• Last Update Submitted That Met QC Criteria: May 14, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: prostate biopsy; targeted biopsy
• Other Study ID Numbers: 20260146

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data (IPD) underlying the results reported in the primary publication, along with the study protocol and statistical analysis plan (SAP), will be made available to qualified scientific researchers. Data will be available beginning 6 months and ending 36 months following article publication. To gain access, researchers must submit a methodologically sound study proposal to the corresponding authors. Data sharing will be strictly subject to the execution of a formal data use agreement and must fully comply with local institutional review board (IRB) requirements and national data security regulations regarding cross-border data transfer.
• IPD Sharing Time Frame: 1 year after publication
• IPD Sharing Access Criteria: kuohaiandrew2000@vip.sina.com
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No