Malignant obstruction of the gastrointestinal tract is a serious complication, occurring in up to 20 percent of patients with upper gastrointestinal cancers and 30 percent of patients with colorectal cancers.
The most common types of malignancies causing small-bowel obstruction are primary cancers of the pancreas and stomach, as well as metastases to the duodenum and jejunum from breast and ovarian cancers. The conventional approach to the treatment of malignant small-bowel obstruction is to perform a surgical gastroenterostomy, with the aim of alleviating symptoms and allowing enteral nutrition.
Malignant colonic obstruction, on the other hand, is primarily caused by colorectal cancers. The conventional management of this is to surgically resect the tumor, followed by a temporary colostomy with the aim of reanastomosis at a later date. However, if the tumor cannot be resected, a permanent surgical colostomy is created instead.
Although the surgical approaches to the alleviation of malignant gastrointestinal obstruction can be effective, they are unfortunately associated with significant morbidity and mortality. Surgical gastroenterostomies have complication rates of 25 percent to 35 percent and mortality rates of two percent. The mortality rates associated with the emergent surgical management of malignant colonic obstruction are even higher at 45-50 percent, with significant morbidity seen in 15-20 percent of patients.
Self-expanding metal stents (SEMS) are novel alternatives to surgery in the management of malignant gastrointestinal obstruction and have been in use since the early 1990s. They are cylindrical tubes composed of metal alloys and are available in a wide range of lengths and diameters. Most stents have a proximal and distal flare to prevent migration. SEMS are generally packaged in a compressed form and constrained in a delivery device. The stent in the delivery system is then deployed across the malignant stricture during endoscopy. In this review, we examine the use of enteral SEMS in the management of malignant gastroduodenal and colonic obstructions.
Technique of Enteral Stent Placement
SEMS are usually deployed under fluoroscopic guidance with the patient in the left lateral position. At endoscopy, a 0.035 inch guide wire is first advanced across the stricture. A ERCP cannula is then advanced over the guide wire and contrast is injected to assess the length of the stricture. After measuring the length of the malignant stricture, a stent of appropriate length and diameter is chosen so as to bridge the stricture adequately. The SEMS delivery system is then advanced over the guidewire and after satisfactory position of the delivery catheter is confirmed by fluoroscopy, the SEMS is deployed.
Gastroduodenal Stents
Success rates: High technical success rates have been reported with gastroduodenal stents, with most investigators achieving stent insertion at the site of obstruction in over 90 percent of cases and several even accomplishing technical success rates of 100 percent. In patients who received these stents, symptomatic improvement was observed in over 80 percent of patients, with majority of patients resuming oral intake or upgrading their oral diet post-procedure.
In studies directly comparing gastroduodenal stents with surgical gastroenterostomy, both methods were comparable in terms of overall mortality. However, stent insertion was a significantly quicker procedure than surgery and patients receiving gastroduodenal stents were able to start oral diets significantly earlier than those undergoing surgical interventions. Additionally, patients receiving stents had a significantly shorter duration of hospital admission than those undergoing surgery.
Complications: As with any endoscopic procedure, gastroduodenal stent placements are associated with complications that include perforation of the gastrointestinal wall in 0.7-5 percent of patients, bleeding in five percent and stent migration or obstruction in 9 percent. One study reported that 25 percent of patients who had received gastroduodenal stents had to undergo additional procedures due to redevelopment of symptoms. However, in a meta-analysis of nine studies, although no difference in 30-day mortality was observed between patients receiving stents and surgical gastroenterostomies, patients in the stent group were significantly less likely to develop complications.
Costs: Gastroduodenal stents appear to be less expensive than surgical gastroenterostomies. In one study by these authors which compared the cost between stents and surgical gastrojejunostomies using data from the Medicare Provider Analysis and Review, the median cost involved with stent insertion was $15,279, compared to $27,790 for surgery. These findings were corroborated by another study, which calculated the cost involved in stent insertion to be $9,921, whereas that for surgical gastrojejunostomy was significantly higher at $28,173.12 Finally, in a decision analysis model which examined the efficacy of stents, open gastrojejunostomies and laparoscopic gastrojejunostomies in the treatment of malignant gastroduodenal obstruction, it was concluded that the use of stents was the most economical choice at a cost of $8,213. In comparison, performing an open gastrojejunostomy was the least economical option of the three, with a cost of $12,191.
Colorectal Stents
Success rates: High success rates have been achieved with the use colorectal stents in malignant colonic obstruction. Studies have shown that over 85 percent of stents are correctly placed at the site of obstruction and some investigators have reported technical success rates of 100 percent. Crucially, 85-95 percent of patients with correctly placed stents experienced an improvement in their symptoms and furthermore, 60 percent to 95 percent of these patients were able to successfully undergo tumor resection with immediate anastomosis in a one-step surgery (bridge-to-surgery) at a later date. Additionally, the stents remained patent during the follow-up period in 64-91 percent of cases.
The issue of one- versus two-stage procedures is an extremely important one in patients presenting with malignant colonic obstruction. In a one-stage surgery, the tumor is resected and the two ends of the colon are immediately rejoined together during the same laparotomy. However, in the two-stage procedure, a diverting colostomy is created initially and then an attempt is made in the future to reanastomose the two free ends of the colon. It is clear that patients undergoing emergency surgical colostomies are more likely than those undergoing stent insertion to have permanent colostomies and this is disadvantageous as they are associated with significant morbidity, as well as having a negative impact on quality of life.
In studies comparing the efficacy of colorectal stents with surgical colostomies, the use of stents was at least as effective as surgery in terms of symptomatic relief, resulting in an improvement in quality of life and was also associated with significantly shorter hospital stays. Furthermore, the use of stents was associated with significantly higher rates of single stage surgeries. In one study involving 48 patients with left-sided colorectal cancers, no patients in the stent group needed permanent colostomies, compared with six patients who initially received surgical colostomies. This was also the case in the study by Martinez-Santos et al, where 85 percent of patients receiving stents prior to surgery were able to undergo single stage procedures with immediate anastomosis, compared to just 42 percent in the surgery group. Another study estimated that the use of stents decreased the need for colostomies by 83 percent.
Complications: Colorectal stent placement is also associated with complications that include bowel perforation, hemorrhage, stent migration and obstruction. Perforation is considered to be the most serious of the complications and its incidence has been reported as ranging from 3.8-10 percent. In comparison with surgical colostomies, the use of colorectal stents was associated with lower acute-complication rates.Also, serious complications occurred significantly more frequently in surgical patients compared to the stent group, with one study showing the incidence of serious complications to be 12 percent in the stent group and 42 percent in the surgery group.
Additionally, a significantly higher proportion of surgical patients appear to require a repeat procedure, with one study quoting a rate of 17 percent for surgical patients compared to 0 percent for the stent group.26 In the study by these authors, 25 percent of patients who had surgery for malignant colonic obstruction had to be readmitted for further reinterventions, compared to 0 percent of patients who underwent stent placements.
Finally, in some studies, the mortality rates appear to be significantly less in patients undergoing stent placement rather than surgical colostomies. In a decision analysis study, the mortality rate in patients receiving a stent and then elective surgery was five percent, where as that for patients having colostomies and then elective surgery was 13 percent.
Costs: The use of stents in the management of malignant colonic obstruction appears to be significantly cheaper than surgical colostomies. In a study conducted by these authors, the hospital cost per Medicare claim was $15,071 for stents and $24,695 for colostomies.
Conclusion
It can be seen that the use of self-expandable metal stents in patients with malignant obstruction of both the upper and lower gastrointestinal tract is just as effective as surgical interventions, while being safer and cheaper. Therefore, stents are valid alternatives to both gastroenterostomies and colostomies in the management of these patients.
Ji Young Bang, MD, is a resident of internal medicine at the University of Alabama at Birmingham, in Birmingham, Ala.; Ann Roy, MPH, is a senior manager of health economics & reimbursement at Boston Scientific Corporation, in Marlborough, Mass; Shyam Varadarajulu, MD, is the chief of endoscopy at the University of Alabama at Birmingham Medical Center and an associate professor of Medicine at the University of Alabama at Birmingham, in Birmingham, Ala.
