Background:
To assess how centralisation of cancer services via robotic surgery influenced positive surgical margin (PSM) occurrence and its associated risk of biochemical recurrence (BCR) in cases of pT2 prostate cancer (PC).

Methods:
Retrospective analysis of all radical prostatectomy (RP) cases performed in the West of Scotland during the period from January 2013 to June 2022. Primary outcomes were PSM and BCR. The secondary outcomes compared the impact of centralisation and surgical approach on PSM and BCR; and margin length and location on BCR. Propensity score matching and Cox regression models were performed using R.

Results:
A total of, 907 patients were included; 662 robot assisted radical prostatectomy (RARP), 245 open RP. PSM rate was 17.7% (161/907), similar in RARP and open cohorts. Patients with PSM had higher rates of BCR; 26.7%, compared to 8.7% in patients with no PSM. Patients with margins of ≥ 1 mm had higher risk of developing BCR. Patients who underwent open RP had increased incidence of PSM ≥ 1 mm; 40/43 (93%) compared to 83/117 (71%) in robotic approach (p = 0.003). Limitations include the study being retrospective, introduction of centralisation and robot concurrently, and evolution of practice.

Discussion:
PSMs in pT2 PC are associated with higher rates of BCR. Introduction of centralisation via the robot had no impact on PSM occurrence or BCR, although did demonstrate a reduction in PSM length.