Oncologic Relevance and Anal Preservation Potential of Transanal Total Mesorectal Excision for Rectal Cancer Invading Adjacent Organs.

Background/aim: Locally advanced rectal cancer (LARC) with adjacent organ invasion presents significant surgical challenges, particularly in achieving negative circumferential resection margins (CRM). Transanal total mesorectal excision (TaTME) offers improved visualization and dissection in the deep pelvis, potentially enhancing oncologic and functional outcomes. This study evaluates the feasibility, oncologic safety and the possibility of anal preservation of TaTME in cT4b rectal cancer requiring combined organ resection.

Patients and methods: This retrospective study analyzed 19 patients with cT4b rectal adenocarcinoma undergoing combined organ resection between January 2015 and December 2023. Surgical approaches included TaTME (n=4) and conventional transabdominal techniques (n=15). Patients requiring total cystectomy or combined uterine and posterior vaginal wall resection were included. Surgical parameters, postoperative complications, and oncologic outcomes were compared. Statistical analyses were conducted using Fisher's exact test and Student's t-test, with significance set at p<0.05.

Results: TaTME demonstrated superior anorectal preservation rates (100% vs. 33%; p=0.1772) and comparable surgical outcomes, including operative time (585 min vs. 550 min) and blood loss (397 ml vs. 380 ml). Negative distal margins were achieved in all cases, although tumor-positive resection surfaces were observed in 13% of conventional cases (p=0.0787). Local recurrence was absent, with minimal distant metastases reported.

Conclusion: TaTME is a safe and effective approach for cT4b rectal cancer, enabling enhanced pelvic dissection and anorectal preservation. While technical challenges remain, TaTME complements conventional methods, particularly for low rectal tumors, offering potential for improved functional outcomes and quality of life in select patients.