**7. Possible promotors and factors to CAL**

Relatively little is known about CAL pathophysiology. Studies, however, have identified several surgical and patient-related risk factors that can influence CAL development. Many factors that can increase the risk of CAL have been analyzed over the years. Among those considered the most important and influential are described: male gender, comorbidities (diabetes, chronic kidney failure, ischemic heart disease, ischemic stroke), type approach, protective ostomy, multiple linear staplers use, blood transfusion, surgery for cancer, and distal colorectal anastomosis was associated with the higher odds of CAL and were identified as independent risk factors [18]. Some are not modifiable, but others can and should be changed to reduce the risk of CAL. The knowledge and identification of independent risk factors for CAL allowed the creation of nomograms for the prediction of anastomotic leakage after anterior colorectal resection [30].

#### **7.1 Non-modifiable factors that may contribute to anastomotic leak**

### *7.1.1 Male gender and patient age*

**Male gender** as a risk factor of CAL is consensual and is named on meta-analyses and several studies with multivariate analysis [19, 31]. It is usually related to surgery for distal rectal cancer due to narrow male pelvic that implies major complex surgery dissection and need of multiple stapling lines rectal stump section. According to some authors, this risk factor associated with distal rectal cancer and neoadjuvant radiotherapy is an indication to make a stoma diversion.

**Patient age** (>65 years old) is rarely considered an independent risk factor [32] more than age, the patient's comorbidities influence the risk of CAL.
