Staged Turnbull-Cutait Pull-through Anastomosis Comparing With Direct Anastomosis Plus Prophylactic Ileostomy in the Treatment of Low Rectal Cancer After Internal Sphincter Resection (STAR-TAR):study protocol for a randomized controlled trial

Abstract Background Recent advancements in the understanding of lower rectum anatomy, rectal cancer biology, and surgical techniques have emphasized the importance of radical surgery for low rectal cancer that balances oncological safety and anal function preservation. After total mesorectal excision (TME) and coloanal anastomosis, participants face high risks of anastomotic leakage and infection, often requiring a protective ileostomy. However, ileostomies themselves lead to significant complications, such as dehydration and chronic renal failure, and many participants cannot have their stomas reversed as planned. The Turnbull-Cutait procedure, involving delayed transanal pull-through rectal resection, has emerged as a safer alternative, reducing leakage complications and avoiding the need for a protective stoma. Recent studies support its use in challenging rectal cases, showing comparable or better outcomes than standard techniques. Despite these promising results, limited data exists on its application to intersphincteric resection (ISR) or intersphincteric dissection (ISD) , which itself has higher complication rates. Therefore, further research is needed to evaluate this Turnbull-Cutait anastomosis procedure (delayed transanal pull-through) in ISR, comparing its complications, oncological outcomes, and functional results to those of traditional methods (direct anastomosis). Methods/design This study is a prospective, multicenter, 1:1, non-inferiority, randomized controlled trial with 110 participants, divided into two groups: the Staged Turnbull-Cutait Pull-through anastomosis group (n=55) and the Direct anastomosis group (n=55). The control group will undergo ISR with traditional anastomosis plus protective ileostomy, while the experimental group will receive the transanal pull-through and delayed anastomosis without ileostomy. The primary outcome is the 30-day overall postoperative complication rate, including anastomotic leakage, infection, and other complications. Secondary outcomes include long-term complications, total surgery time, anorectal function (measured by LARS and Wexner scores), urinary and sexual function, quality of life (EORTC QLQ–CR29 and FIQL), and three-year disease-free survival (DFS) and overall survival (OS). Discussion Currently, there is a lack of systematic studies exploring the use of delayed pull-through anastomosis in intersphincteric resection (ISR) procedures. Existing research on this technique in low rectal cancer is limited to small, single-center, retrospective studies with low levels of evidence. Therefore, a multicenter, prospective, randomized controlled trial is needed to determine whether delayed pull-through anastomosis can serve as a viable alternative to ISR-coloanal anastomosis, offering comparable or lower rates of postoperative complications, as well as similar oncological outcomes and defecatory function. This study aims to provide higher-quality evidence through a larger, well-designed trial, which could significantly inform clinical practice in this under-explored area. Trial registration ClinicalTrials.gov NCT06662643. Registered on October 29, 2024.