Predictors of Rescue Surgery, Mortality, and Permanent Stoma After Anastomotic Leak Following Colorectal Cancer Resection

Anastomotic leakage is a serious complication following colorectal cancer resection and may result in emergency reoperation, severe sepsis, death, loss of the colorectal anastomosis, and formation of a long-term or permanent intestinal stoma. This multicentre observational cohort study will investigate patients who develop an anastomotic leak following colorectal cancer resection with primary anastomosis. The study will evaluate patient-related, tumour-related, operative, biochemical, radiological, leak-related, and treatment-related factors associated with three major outcomes: unplanned rescue surgery, 90-day mortality, and permanent stoma formation. No treatment will be assigned by the investigators. Diagnosis and management of anastomotic leakage will be determined by the treating surgical teams according to their usual clinical practice. Participants will be followed for at least 12 months after the index colorectal resection. The results may help clinicians identify high-risk patients, improve the timing of intervention and source control, support discussions with patients and families, and develop future risk-prediction models for anastomotic leak outcomes.

Inclusion Criteria: * Age 18 years or older. Histologically confirmed or clinically suspected primary colorectal adenocarcinoma requiring surgical resection. Undergoing elective or emergency colorectal resection with formation of a primary intestinal or colorectal anastomosis. Anastomotic leakage diagnosed within 90 days after the index colorectal resection or during the index hospital admission. Leak confirmed clinically, radiologically, endoscopically, through drainage of enteric contents, or during operative exploration. Availability of sufficient medical records to determine the method of leak diagnosis, treatment, and short-term outcomes. Ability to complete follow-up for stoma status, where applicable. Exclusion Criteria: * Age younger than 18 years. Colorectal operation performed for a benign condition without colorectal cancer. Abdominoperineal excision or another procedure without formation of an intestinal anastomosis. Local transanal tumour excision without colorectal anastomosis. Leakage involving only a urinary, vascular, or non-intestinal anastomosis. Planned permanent stoma without a colorectal or intestinal anastomosis. Anastomotic leak occurring after surgery for recurrent disease without resection of a primary colorectal tumour, unless specifically included in a predefined secondary cohort. Inability to verify the diagnosis of anastomotic leakage. Inadequate data to determine all three primary outcomes. Refusal to participate where individual informed consent is required.