This is a nationwide prospective observational study to assess the overall clinical anastomotic leakage rate after right hemicolectomy for cancer, to detect the independent risk factors for AL, and to develop a clinical prediction model to estimates of the probability of the occurrence of an AL after surgery. Since this is a multicenter prospective study, the Division of Surgical Oncology and Digestive Surgery from the University of Turin, Department of Oncology, AOU San Luigi Gonzaga di Orbassano will be the Coordinator Center of the study, Ethics committee approves will be requested before the implementation of this study.

Italian high-volume colorectal surgery centers members of SICO (The Italian Society of Oncological Surgery) have agreed to participate as collaborators of this study, notification and revision from their local ethics committee will be requested as well. A certified general surgeon with a large experience in the preoperative, operative, and postoperative management of patients with colorectal cancer has been identified to coordinate the study in each center. Id information of the potential collaborators is specified in the section "Trial Setting". Once the study is activated, eligible patients (or a representative) must provide written, informed consent before any study procedures occur. No intervention or modification of the habitual clinical practice is planned All data will enter into a database provided by the promoting center. There are three main sections of data collection for each patient:

• Preoperative: baseline, disease and demographics.
• Operative: details about the surgery, anastomosis construction and enterotomy closure.
• Follow-up: outcomes data about the early (within 30 postoperative day) and late postoperative course (31 th - 60th postoperative day) and pathology report. The definition of AL is based on the presence of clinical signs (pain, fever, tachycardia, peritonitis, feculent or enteric drainage, purulent drainage, postoperative ileus, abscess, septicemia, and/or organ failure) with radiographic signs (fluid collections, gas containing collections at CT scan) suggestive of AL and-or intraoperative or autopsy findings (gross enteric spillage, anastomotic disruption). The absence of AL will be assumed by a normal postoperative course and the absence of symptoms suggestive of AL with or without radiologic confirmation.

Inclusion Criteria:

• Patients from all participating centers older than 18 years, males or females, with the diagnosis of primary right colon cancer including the cecum, ascendent, liver flexure, and proximal third of the transverse colon, in both emergency and elective settings, with the indication of RH, referred as to the resection of a portion of the distal ileum, cecum, ascending colon, and proximal to the mid-transverse colon, with intraperitoneal or extraperitoneal primary handsewn or mechanical ileocolic anastomosis by minimally invasive(robotic or laparoscopic) or open approach.

Exclusion Criteria:

• -Long steroid treatment for any cause.
• Right colon resection for benign disease.
• History of supra-mesocolic space radiotherapy.
• Inflammatory bowel disease (Crohn's disease and ulcerative colitis). No healthy volunteers are accepted.

Patients from all participating centers older than 18 years, males or females, with the diagnosis of primary right colon cancer including the cecum, ascendent, liver flexure, and proximal third of the transverse colon, in both emergency and elective settings, with the indication of RH, referred as to the resection of a portion of the distal ileum, cecum, ascending colon, and proximal to the mid-transverse colon, with intraperitoneal or extraperitoneal primary handsewn or mechanical ileocolic anastomosis by minimally invasive(robotic or laparoscopic) or open approach.