3D-printed model for resection of positive surgical margins in robot-assisted prostatectomy

Objectives: To improve precision of secondary resection (SR) after positive surgical margin (PSM) detection by frozen section (FS) during nerve-sparing (NS) robot-assisted radical prostatectomy (RARP) by employing a personalised three-dimensional (3D)-printed prostate model derived from pelvic magnetic resonance imaging (MRI). This model was used to mark positive surgical margins (PSM) and guide intraoperative SR during NS-RARP.

Patients and methods: Prospective multicentre cohort study with 100 patients undergoing NS-RARP between September 2018 and August 2021. Primary and secondary endpoints were the conversion rate of FS-identified PSM to a tumour-free margin and functional/oncological parameters within a 12-month follow-up, respectively.

Results: A PSM was identified in 23% of cases during FS, with a conversion to negative surgical margins (NSM) in 83% (19/23 cases) by model-guided SR. The tumour detection rate in SR specimens was 39% (nine of 23 cases). Among the 19 patients with converted margins, 18 (95%) achieved undetectable prostate-specific antigen levels 2 months postoperatively, with six (32%) having subsequent biochemical recurrence within 12 months. prostate-specific-membrane-antigen positron emission tomography computed tomography found one local recurrence, and five cases of metastatic disease. In converted patients, the baseline median five-item version of the International Index of Erectile Function score decreased by 16% after 1 year, with no significant difference compared to patients with primarily NSM. Limitations include the absence of a control group, the potential for false-negative FS results and limited accuracy of MRI.

Conclusion: The integration of 3D-printed prostate models into NS-RARP has the potential to positively impact surgical outcomes by improving the precision of SR and optimising pathosurgical communication.