Aim: Accumulated data suggest that routine use of defunctioning stoma in low anterior resection for rectal cancer may cause kidney injury, bowel dysfunction and a higher risk of permanent stomas. We aim to study whether avoidance of a diverting stoma in selected patients is safe and reduces adverse consequences.

Methods: SELSA is a multicentre international prospective observational study nesting an open-label randomized clinical trial. All patients with primary rectal cancer planned for low anterior resection are eligible. Patients operated with curative intent, aged <80 years, with an American Society of Anaesthesiologists' fitness grade I or II, and a low predicted risk of anastomotic leakage are eligible to 1:1 randomization between no defunctioning stoma (experimental arm) or a defunctioning stoma (control arm). The primary outcome is the composite measure of 2-year stoma-free survival without major low anterior resection syndrome (LARS). Secondary outcomes include anastomotic leakage, postoperative mortality, reinterventions, stoma-related complications, quality of life measures, LARS score, and permanent stoma rate. To be able to state superiority of any study arm regarding the main outcome, with 90% statistical power and assuming 25% attrition, we aim to enrol 212 patients. Patient inclusion will commence in the autumn of 2024.

Conclusion: The SELSA study is investigating a tailored approach to defunctioning stoma use in low anterior resection for rectal cancer in relation to the risk of anastomotic leakage. Our hypothesis is that long-term effects will favour the selective approach, enabling some patients to avoid a defunctioning stoma.