The Challenge: Anastomotic Leakage
Overview of Anastomotic Leakage
Colorectal cancer (CRC) is the second most common form of cancer and the third most common cancer cause of death in Europe, with an aged-standardized incidence rate of 48 cases per 100,000 in 2008 (data from European Cancer Observatory). CRC is generally a condition associated with the elderly, with a mean age at diagnosis of 73 years. At least 50% of the Western population develop some form of CRC by the age of 70, spanning the spectrum from an early benign polyp to an invasive adenocarcinoma. The curative management of CRC is mainly surgical and is based on the resection of the affected bowel. At the extremities of the resection the bowel segment must be surgically sutured to restore normal bowel transit. The site at which bowel continuity is restored is called the anastomosis and the operation can be performed manually or mechanically through staplers. The most frequent and feared post-operative complication of any bowel resection with immediate anastomosis is “Anastomotic Leakage” (AL). AL occurs when incorrect and rapid regeneration of the intestinal tissue takes place at the site of the anastomosis. The incidence of AL depends on the segment of colon involved and on the kind of operation performed: the general incidence averages approximately 10%; it can be much lower for the proximal colon and higher in the cases of distal rectal cancers. The rate of AL after rectal cancer surgery varies according to different countries reaching up to 21% of patients and leading to mortality rates of up to 39.3% .
About Colorectal Resection and Anastomosis
Colorectal resection is the treatment of choice for the cure of large bowel cancer. The operation can be performed laparoscopically or with a classic open approach and there is no significant difference in the incidence of anastomotic leakage between the two techniques. Furthermore, the anastomosis can be realized by hand-sewing or by mechanical stapling devices: no statistically different rates of leaks have been shown in the literature.
After resection on the cancer tissue, the surgeon typically performs the anastomosis by handsewing or stapling techniques; improvements in safety aspects of such procedures are being sought. Technical improvements like the use of staple line or circular reinforcements (e.g. Gore® SeamGuard®) have only slightly decreased the rate of leakage in these operations; nevertheless the high mortality and severe morbidity in patients suffering from AL justify the necessity of additional methods for decreasing the rate of failure. A reinforcement with a material that wraps the anastomosis is considered a better, solution by surgeons. Such external reinforcement can be released by the stapling device or applied exogenously to the staple line. The wrapping material should be prepared in the form of patch or sleeve, must be biocompatible, water swellable and easy to handle also in connection with laparoscopic techniques. Moreover, the choice of the material must take into consideration the risk of postoperative intra-abdominal adhesions which can lead to inflammation and infection; thus there is the need of a material that does not cause adhesions between viscera and abdominal wall.
Currently no products exist which have been developed specifically for the prevention of AL.
Factors Contributing to Anastomotic Leakage
Both systemic and surgical factors contribute to the onset of AL: malnutrition, metabolic diseases, organ failure, old age, and immunosuppression are considered the main systemic risk factors. The surgical technique can favour AL especially when excessive skeletonization of the proximal colonic stump occurs, reducing its vitality. A technically difficult operation is also one of the leading surgical causes of AL; a narrow and deep pelvis, the presence of a bulky tumor, and a more advanced local stage of disease are some of the possible frequent and unpredictable scenarios. However, AL also occurs in patients with no obvious risk factors. Specifically for low rectal cancer, neoadjuvant therapy is considered an additional risk factor for AL.
Signs and Symptoms
From a clinical point of view, leakage may present itself in different ways: as ageneralized peritonitis requiring abdominal reoperation, a more localized collection that may be drained, or as a subclinical leak detected merely on contrast radiology. The patients developing this complication generally need an additional number of radiographic studies, have a longer hospital stay, need extra nursing and medical care and very often will require a reintervention, with subsequent increase in morbidity and mortality. When an AL is present, the associated risk of post-operative mortality is increased to between 6 and 22%. In addition, adjuvant chemotherapy, when indicated, is delayed with subsequent worsening of the prognosis. AL is associated with a significant increase in local recurrence of cancer and a decrease in long-term survival. In a Dutch dedicated colorectal cancer center the 5-year local recurrence rate was 8.8% for patients without anastomotic leakage and 12.0 for those with a leak; the 5-year overall survival was 74.4% in the first group and 66.4% in the second. Concerning long-term complications, AL is also one of the most common causes of anastomotic strictures. The incidence of colorectal anastomotic strictures varies from 3 to 30%. Most of these strictures are simple narrowings shorter than 1 cm that can be successfully treated by dilation or endoscopic alternatives. However, up to 28% of patients will require further surgical correction. In patients with low rectal cancer AL is one of the causes of poor functional results in terms of faecal continence. Overall AL is a severe common complication which affects mainly the aging population after CRC resection. This complication is associated with high disability, diminished quality of life and high costs for heath and long term care.