Margin Matters: Analyzing the Impact of Circumferential Margin Involvement on Survival and Recurrence After Incomplete Total Mesorectal Excision for Rectal Cancer

Abstract Backgorund: Incomplete mesorectal excision during rectal cancer surgery often leads to positive circumferential margins, with uncertain prognostic impacts. This study examines whether negative margins can mitigate the poorer prognosis typically associated with incomplete TME in rectal cancer surgery, thus potentially challenging the prevailing emphasis on complete mesorectal excision. Methods A retrospective analysis was conducted on patients who underwent proctectomy for rectal adenocarcinoma with incomplete TME at a single center from 2010–2022.Patients were stratified by margin status as determined by pathologic analysis into three groups: involved,not involved with closest margin distance ≤ 2mm,and not involved with closest margin distance > 2mm. Outcomes included recurrence and survival. Effects of neoadjuvant therapy protocols on margin status was also assessed. Results From 2010 to 2022, 7,941 patients underwent proctectomy for rectal cancer, with 236 (3%) having incomplete TME. The median age of these patients was 64 years,and 63% were male.Overall, margin involvement was observed in 54 (23%) patients. The median tumor size was 3.05 (IQR: 2–6) cm for the whole group. Involved margins (23.2%) had reduced overall survival (60.5 vs 87.3 months, p 2mm vs ≤ 2mm) did not affect outcomes. Total neoadjuvant therapy (vs standard chemoradiation)was associated with lower involved margins (p = 0.007). Conclusions Positive margins retain negative prognostic impact with incomplete TME. Optimization of surgical resection remains vital. Total neoadjuvant therapy may decrease risk of incomplete TME.