Anastomotic leak (AL) is one of the most feared complications after colon cancer (CC) surgery. The incidence varies according to the studies, the definition used and the location of the excised segment.

In some of the series described, AL incidence have hardly changed, despite the evolution of the technique and technological improvements. The leak rate obtained in the only Spanish prospective multicenter observational study at national level was 9% (ANACO study).

The aim of the present study is to determine the current rate of AL in our country, 10 years after the ANACO study, to determine if there has been any evolution and to analyze the factors associated with it. For this purpose, AL is defined with the same criteria as in the first study, as leakage of luminal contents through the junction between two hollow visceras, diagnosed radiologically (radiography with soluble enema or CT with collection adjacent to the anastomosis), clinically (extravasation of luminal contents or gas through the wound or drainage), endoscopically or intraoperatively. To compare AL rates throughout this decade, a 60-day follow-up will be performed, the same as in the ANACO study.

As a modification respect to the ANACO study protocol, the aim is to analyze the possible influence of AL and perioperative intra-abdominal infection on short-term oncologic prognosis, with a one-year follow-up. This question has hardly been studied in prospective multicenter studies to date.

The variables to be collected are divided into demographic (information about the hospital center, patient comorbidities), diagnostic variables (analytical values, diagnostic reason, neoadjuvant, localization, TNM), surgical variables (type of surgery, preparation, intention, intraoperative findings and complications, type of resection and anastomosis), admission (AL, other complications), histology, 60-day follow-up (AL, readmissions), one-year follow-up (readmissions, local recurrence, peritoneal and distant recurrence).

Patients included in the study must be >18 years old undergoing oncologic surgery for CC located 15 cm above the anal margin, with preoperative histological confirmation or with endoscopic suspicion of infiltrating lesion or with radiological suspicion in the context of urgent surgery. Intestinal continuity (anastomosis) should be reconstructed and a derivative stoma should not be associated in the same surgery. According to ANACO data and follow-up times according to the primary objective (AL) at 60 days and the secondary objective (oncologic prognosis) with annual follow-up, inclusion will be carried out until the 1628 individuals required according to the sample size calculation performed are included.

Inclusion Criteria:

• >18 years old undergoing oncologic surgery for CC located 15 cm above the anal margin, with preoperative histological confirmation or with endoscopic suspicion of infiltrating lesion or with radiological suspicion in the context of urgent surgery. Intestinal continuity (anastomosis) should be reconstructed in the same surgery.

Exclusion Criteria:

• Derivative stoma in the same surgery
• Palliative surgery
• Definitive stoma creation without anastomosis

Oncologic surgery for colon cancer located 15 cm above the anal margin, with preoperative histological confirmation or with endoscopic suspicion of infiltrating lesion or with radiological suspicion in the context of urgent surgery

It is the intention of the authors to share data collected through an official data repository such as Mendeley, for example.

From three months after recruitment after 3 months of follow-up ending.

Under demand.