Oncologic and survival outcomes of pT2N0 rectal adenocarcinoma treated by transanal local excision: a retrospective cohort study.

Background: The optimal management of pT2N0 rectal adenocarcinoma remains controversial, especially when tumours are incidentally diagnosed after local excision. Although total mesorectal excision (TME) is the standard approach, its associated morbidity has led to the exploration of conservative strategies. This study compares oncologic outcomes amongst three post-excision management options: salvage surgery, adjuvant radiotherapy, and no further treatment. Methods: This retrospective cohort comprised 90 patients with pT2N0 rectal adenocarcinoma who were treated by transanal excision at a single tertiary centre from 1993 to 2025. All patients were staged N0 on MRI and divided into three groups: Group A (no further treatment), Group B (adjuvant radiotherapy), and Group C (completion salvage surgery). The primary outcomes were overall survival (OS) and disease-free survival (DFS), with additional analyses of histopathologic prognostic factors. Results: Median follow-up was 31 months. OS varied significantly across groups (p = 0.015), with the highest survival in Group B, followed by Group C and Group A. DFS showed no significant difference between groups. Patients in Group B had the lowest mortality (8.7%) and recurrence (30.4%) rates. Tumour budding was a significant predictor of poor prognosis in multivariate analysis. Local excision alone was associated with higher recurrence and mortality rates. Conclusion: In selected patients with pT2N0 rectal cancer discovered after transanal excision, adjuvant radiotherapy may provide outcomes comparable to salvage surgery and serve as an alternative in patients not suitable for surgery. High-risk histopathologic features should inform further management, as local excision alone was associated with worse outcomes. Multidisciplinary evaluation remains crucial for treatment planning.