SRS264 - Avoidable positive surgical margins after robotic-assisted radical prostatectomy

Abstract Introduction Positive surgical margins (PSM) after robotic-assisted radical prostatectomy (RARP) can lead to negative oncological outcomes. This study aimed to identify sources of avoidable PSMs to improve outcomes. Methods Data from 100 consecutive cases with PSMs in 2022 were extracted for biopsy and MRI cancer location identification, RARP planning recommendations, surgeon operation notes, and final pathology results. Exclusion criteria were Neurosafe procedures, absence of pre-operative MRI, or undocumented RARP planning. PSMs were identified at staging, planning, and/or execution and classified as avoidable or unavoidable based on available information and decision-making. Results Out of 100 patients, 45 had extracapsular extension (ECE). 112 distinct PSMs were identified and classified as apical (32%, n = 36), basal (8%, n = 9), anterior (3.5%, n = 4) or postero-lateral (56%, n = 63). 49% of PSMs were intra-prostatic (n = 55). Sources of PSM included staging (28.5%), planning (∼20%) and execution (∼52%). However, ∼90% of execution errors were unavoidable, with PSMs occurring most commonly despite no function-sparing (∼70%) or adherence to the planning recommendation. Conversely, all planning errors were avoidable and occurred due to inappropriate functional sparing (78%), or unrecognised ECE or overlooked patient factors. Meanwhile, within staging errors, ∼28% were avoidable due to biopsy errors while the remaining were unavoidable (MRI-invisible disease). The most common avoidable PSM was due to inappropriate intra-fascial nerve-sparing recommended in the planning stage. Conclusions Overall, ∼30% of PSMs were avoidable. Reductions are achievable through improving biopsy targeting accuracy and MRI interpretation. Adherence to surgical planning and ongoing technical refinement can further improve oncological outcomes.