What are the risk factors for anastomotic leakages after surgical resection for colorectal cancer?

This review analyzed a number of studies evaluating the risk factors for anastomotic leakage in patients undergoing colorectal cancer resection.

Colorectal resection, defined as the surgical removal of part of the colon or rectum with cancerous cells, is usually the main treatment for colorectal cancer. After resection, an anastomosis (a surgical connection between two structures) is often performed to restore intestinal continuity. Anastomotic leakage is among the most significant postoperative complications. Anastomotic leakage is a breakdown along an anastomosis which causes body fluids to leak. The true risk factors for colorectal anastomotic leakage remain uncertain.

This review included 23 studies evaluating 110,272 patients undergoing colorectal cancer resection. The overall leakage rate for anastomoses was 7.2%. An analysis of 17 studies evaluating gender as a risk factor found that male gender was a significant risk factor for anastomotic leakage. An analysis of seven studies found that the odds of anastomotic leakages were 1.48 times higher in men compared to women.

13 studies evaluating level of anastomotis as a risk factor of anastomotic leakage suggested that a low rectal anastomosis (defined as an anastomosis performed 5 cm or less from the anal verge) was a significant risk factor for anastomotic leakage. An analysis of six studies found that the odds of anastomotic leakages were 3.26 times higher in patients with low anastomoses compared to those with anastomoses higher in the rectum. The average leakage rate for the low rectal anastomoses was 11.6% compared to 9.2% for the anastomoses higher in the rectum.

Another analysis of two studies suggested that preoperative radiotherapy (treatment of disease using X-rays or other forms of radiation prior to surgical intervention) may be a risk factor for anastomotic leakages. The odds of anastomotic leakages were 1.65 times higher in patients who underwent preoperative radiotherapy compared to those who did not undergo preoperative radiotherapy.

In addition, analysis of studies evaluating ASA-class (a grading system for preoperative health of the surgical patients) as a risk factor for anastomotic leakage suggested that high ASA-class was significantly associated with anastomotic leakages. The higher ASA-class associated with a patient, the less healthy the patient is. The analysis showed that the odds of anastomotic leakages were 1.71 times higher in patients with high ASA-class (less healthy) compared to those with a lower ASA-class (more healthy).

Other studies showed that age, body mass index (a measure of relative weight based on an individual's mass and height) and tumor stage were not associated with anastomotic leakages.

In summary, this review concluded that gender, low rectal anastomoses and preoperative radiotherapy are the most important risk factors for anastomotic leakages in patients who undergo colorectal resection.

The majority of the specific outcomes were mostly a result of the observational nature of the studies included in this review. Thus, these results should be interpreted with caution.