IntAct- IFA to prevent anastomotic leak in rectal cancer surgery

INTERVENTION: 880 participants will be randomised prior to surgery, on a 1:1 basis, to either surgery with IFA or surgery without IFA using minimisation (incorporating a random element) and stratified by surgeon, gender, ASA grade, T‐stage, neo‐adjuvant therapy and tumour position. Participants will receive an anterior resection either with or without IFA (intraoperative fluorescence angiography) depending on their randomised allocation: Surgery with no IFA: The anterior resection (high or low) will be performed according to the surgeon’s usual technique, using either a laparoscopic or robotic approach, with white light assessment of bowel perfusion. The specifics of each operation will be at the discretion of the operating surgeon. Surgery with IFA: The anterior resection (high or low) will be performed according to the surgeon’s usual technique, using either a laparoscopic or robotic approach. ICG (Indocyanine Green) will be administered intravenously at two points during the operation for perfusion assessment using near‐infrared laparoscopy. A third dose of ICG will be permitted (e.g. extracorporeal assessment, or immediately prior to anastomosis) should the surgeon feel this to be beneficial. The specifics of each operation, including the decision to make a change to the planned anastomosis following IFA assessment, will be at the discretion of the operating surgeon. All patients will be followed up until 90 days post‐operation. Patients will be seen in clinic at 30 days and 90 days post operation, and a rectal contrast enema scan will be performed at 4‐6 weeks post operation. Patients will complete quality of life and health resource use questionnaires at baseline, 30 and 90 days post operation. For patients in the microbiome sub‐study (200 UK patients), faecal samples will be taken at baseline, intra‐op and at 3‐5 days post operatively. For patients in the perfusion sub‐study, two additional scans will be performed pre‐operatively (CT angiography and CT perfusion). CONDITION: Specialty: Surgery, Primary sub‐specialty: Colorectal Surgery; UKCRC code/ Disease: Cancer/ Malignant neoplasms of digestive organs ; Cancer ; Colorectal cancer PRIMARY OUTCOME: Clinical anastomotic leak rate is defined as per the International Study Group of Rectal Cancer definition, as a confirmed defect of the intestinal wall at the anastomotic site (including suture and staple lines of neorectal reservoirs) leading to a communication between the intra‐ and extraluminal compartments that has an impact on patient management, as assessed through clinical examination within 90 days post operation INCLUSION CRITERIA: 1. Aged 18 years and over 2. Able to provide written informed consent. 3. Diagnosis of rectal cancer (defined as a lower margin up to 15cm from the anal verge as assessed by endoscopic or radiological assessment) 4. Suitable for curative resection by high or low anterior resection 5. Suitable for elective laparoscopic or robotic surgery 6. ASA less than or equal to 3 7. Able and willing to comply with the terms of the protocol including QoL questionnaires SECONDARY OUTCOME: 1. Change in planned anastomosis during surgery, including the decision to undertake a permanent stoma rather than an anastomosis, the site of proximal bowel used for anastomosis, the site of rectal remnant used for anastomosis, and the decision to undertake a diverting stoma; 2. Rate of defunctioning stoma (temp or permanent) ; 3. Operative and post‐operative complications (Clavien‐Dindo for complication‐level classification and Comprehensive Complication Indicator for patient‐level classification) within 90 days of operation; 4. Length of post‐operative hospital stay; 5. Low Anterior Resection Syndrome (LARS) score at 30 days and at 90 days post‐operation in patients without defunctioning ileostomy; 6. Rate of re‐interventions within 90 days; 7. Quality of life is assessed using the QLQ‐C30, QLQ‐CR29 and EQ‐5D at 30 days and 90 days post‐operation; 8. Health resource utilisation assessed at 30 days and 90 days post‐operation; 9. Death within 90 days of operation; ; Mechanistic sub‐study; 1. Presence of vascular variants, presence of atherosclerosis within IMA; 2. Presence of stenosis (=or >50%) in the internal iliac artery, internal pudendal artery, superior rectal, middle rectal or inferior rectal artery; 12. Difference in regional blood flow, blood volume or permeability surface area product in patient with or without anastomotic leak, no and prior (chemo)radiation, and intra‐operative fluorescence; 13. Changes in rectal microbiome and correlation to anastomotic leak;