Our preliminary work demonstrates that there is buy-in from both patients and surgeons with regards to early ileostomy closure (EIC) for select rectal cancer patients undergoing restorative proctectomy (RP) and diverting loop ileostomy (DLI). The feedback from leaders in Europe further supports the need for a large scale randomized-controlled trial (RCT) on this subject in North America. Should the results of such a study be favourable, we believe it could support a change in practice that would be beneficial to patients and the health care system alike. Furthermore, our work will help identify which patients and practices are suitable for EIC.

The goal of our project is to determine whether EIC in rectal cancer patients undergoing RP with a DLI is safe, feasible and beneficial in a North American population. Specifically, our primary objective is to compare the severity of complications between patients undergoing EIC versus traditional (late) closure. Our secondary objectives include assessing the difference in quality of life (QoL), early and late bowel function, and cost of care between these two groups.

Eligible adults (≥18 years-old) from one a large colorectal surgery practice in Canada who (1) underwent RP with creation of a DLI for the treatment of rectal cancer and (2) have a negative anastomotic leak test on post-operative day 7-9 which will consist of a flexible sigmoidoscopy and CT scan with rectally-administered water soluble contrast. Patients will be excluded if there is (1) peri-operative immunosuppression, (2) age-adjusted Charlson Comorbidity Index >6, (3) other major surgery during the index operation, and (4) any major complications (Clavien Dindo Grade III-V) following RP. Eligible participants will be randomized (1:1): Intervention group (EIC): Following a negative leak test, patients will undergo standardized reversal of their DLI (stapled side-side functional end-to end anastomosis, purse-string closure of the ileostomy wound and no use of epidural analgesia) between post-operative days 10-14. Control group (standard practice): Following a negative leak test, patients will undergo a standardized reversal of their DLI no earlier than 12 weeks following their index surgery.

The primary outcome will be comprehensive complication index (CCI) at 12 months following RP. Secondary outcomes will include: CCI at 2-, 6-, and 9-months following RP; recovery from surgery using the PROMIS 29 profile at 7- and 14-days post RP; bowel function, as measured using the Low Anterior Resection Syndrome (LARS) Score at 2-, 6-, 9-, and 12-months post-DLI closure; post-operative ileus, as defined by intolerance to oral intake in the absence of clinical or radiological signs of obstruction, will be measured prospectively after DLI closure; overall QoL, as measured by the EORTC CR30 and QLQ-CR38 at 0-, 2-, 6-, 9-, and 12-months post-RP; cost, as measured from the perspective of the healthcare system [length of hospital stay (RP, ileostomy closure, and any readmissions), interventions in any setting following RP, and appliance-related costs] will be assessed at 6- and 12-months post-index surgery. Treatment effect on the primary outcome (CCI at 12 months) will be modeled using linear regression.

Inclusion Criteria:

• Adult (≥18 years-old) patients
• Underwent restorative proctectomy by a laparoscopic, robotic, transanal total mesorectal excision, or open approach with creation of a diverting loop ileostomy for the treatment of rectal cancer
• Negative anastomotic "leak test" via CT scan with rectally-administered water-soluble contrast on post-operative day 7, 8 or 9.

Exclusion Criteria:

• Peri-operative immunosuppression (within 6 weeks of surgery date);
• Age-adjusted Charlson Comorbidity Index >6;
• Other major surgery during the index operation;
• Any major complications (Clavien Dindo Grade III or greater) following restorative proctectomy;
• Inability to speak or comprehend English or French and inability to give informed consent.