The aim of this study is to investigate the diagnostic accuracy of the C Protein Reactive (CRP) for the detection of Anastomotic leakage after surgery for digestive cancer. The standard protocol in our unit is to measure the CRP on the second and fourth postoperative day.

The main aim of the study is to investigate the diagnostic accuracy of the ratio CRP on the fourth postoperative day on CRP on the second postoperative day (CRP_D4/CRP_D2). Secondary outcomes are the diagnosis accuracy of the CRP_D4 and CRP_D2.

The occurrence of anastomotic fistula (AF) is the most feared complication after digestive cancer surgery. It is responsible for high morbidity and accounts for more than a third of the deaths observed. The rate of anastomotic fistula reported in the literature varies between 1 and 40% according to the definition chosen by the authors. In the literature, the occurrence of the anastomotic fistula is responsible for a mortality rate of 4% and an overall morbidity of 35%. In the short term, the anastomotic fistula can put the patient's vital prognosis at risk by its septic consequences. Also, it is responsible for increasing the length of stay and costs. In the longer term, anastomotic fistula affects the functional prognosis of the patient as well as oncology in patients operated for cancer.

Early rehabilitation becomes a standard in colorectal surgery, with exits around the 5th postoperative day. Anastomotic fistulas and their complications may appear well beyond. The diagnosis is made on average around 6-7 postoperative days. At an early stage, clinical signs are inconsistent and not very specific. Anastomotic fistula can manifest itself in a variety of clinical presentations, ranging from no symptoms to life-threatening septic shock. Routine imaging is neither reliable nor cost-effective for the detection of anastomotic fistulas and has the disadvantage of radiation.

It is necessary to find an intraperitoneal infection marker with a high negative predictive value. This is particularly important in the era of early rehabilitation, allowing for safe patient discharge with a low risk of readmission. C-reactive protein (CRP) has already shown its utility in the early detection of infections after digestive surgery, however, because of conflicting results, no clear recommendations are established in the literature.

Our study aims are to investigate the diagnostic accuracy of the postoperative CRP trajectory as an approach to eliminate the diagnosis of anastomotic fistula and to try to establish an optimal threshold with high sensitivity and negative predictive value.

Inclusion Criteria:

• Surgical resection for digestive cancer
• Creation of anastomosis.
• at least one measurement of CRP at the second and/or fourth postoperative day.

Exclusion Criteria:

• Surgical resection without anastomosis creation
• No measurement of CRP on the second or the fourth postoperative day.

All consecutive patients who will undergo surgical resection for digestive cancer with the creation of anastomosis will be included. The standard protocol in our unit is to measure the CRP at the second and fourth postoperative days for early detection of anastomotic leakage.

The following information will be recorded: age, gender, type of surgery, type of anastomosis, postoperative morbidity according to Clavien Grade, anastomotic leakage occurrence, infectious complications.