Long-Term Outcomes of Patients with Poor Prognostic Factors Following Transanal Endoscopic Microsurgery (TEMS) for Early Rectal Cancer.

Background: Transanal endoscopic microsurgery (TEMS) is an organ-preserving approach for treatment of early rectal cancer (ERC). However, adverse histopathological features identified post-TEMS often necessitate adjuvant therapy. This study aims to compare the long-term oncological outcomes of patients who underwent TEMS and were offered adjuvant treatments with total mesorectal excision (TME), chemoradiotherapy (CRT), radiotherapy (RT), active surveillance, or dose escalation with contact X-ray brachytherapy (CXB). Methods: This study included patients treated with TEMS for ERC between September 2012 and December 2022, with follow-up until December 2023. Patients with adverse histopathological features (extra-mural venous invasion, lympho-vascular invasion, R1 margins, tumour budding) were assigned to adjuvant treatments. Inverse probability of treatment weighting (IPTW) was applied to mitigate selection bias. Results: Of the 117 patients, 24 underwent TME, 17 received CRT, 25 received RT, 14 underwent active surveillance, and 37 patients received CXB boost along with CRT. The median follow-up was 60 months (IQR 52-73). During this time, 29 patients developed recurrence, and 15 died. The 5-year overall survival (OS) was 78.6%, and disease-free survival (DFS) was 70.9%. Compared to CXB, the mortality risk for CRT (HR = 0.81; 95% CI: 0.20-3.28; p = 0.77) and TME (HR = 3.68; 95% CI: 0.46-29.79; p = 0.22) was not significantly different. However, TME was associated with a significantly higher recurrence risk compared to CXB (HR = 7.57; 95% CI: 1.23-46.84; p = 0.029). Conclusions: An organ-preserving strategy with CRT or CRT combined with a CXB boost may offer comparable long-term outcomes and reduced recurrence risks for patients undergoing TEMS for ERC with poor prognostic features. Further research with larger cohorts is needed to validate these results.