In recent years, endoscopic minimally invasive treatment techniques have made rapid advances. In the treatment of malignant gastrointestinal obstruction, self-expanding metal stents placed through the scope (through the scope, TTS) with a large caliber (≥3.7 mm) endoscopic clamp channel have been gradually applied in the treatment of malignant gastric outlet or duodenal obstruction and malignant colorectal obstruction, and have partially replaced surgical bypass surgery (i.e., emergency laparostomy) while achieving good clinical outcomes. In this article, we will briefly describe the application of intestinal endoprosthesis in gastric outlet-duodenal obstruction and colonic obstruction.
1. Treatment of gastric outlet-duodenal obstruction.
Gastric outlet-duodenal obstruction is a common comorbidity of unresectable distal gastric cancer, duodenal cancer and pancreatic cancer, of which approximately 15-20% of pancreatic cancer patients can develop gastric outlet-duodenal obstruction. Gastric outlet-duodenal obstruction can cause nausea, intractable vomiting, esophagitis, electrolyte imbalance, malnutrition, and severe dehydration. The traditional palliative treatment is open or laparoscopic gastro-jejunal anastomosis. However, even with laparoscopic surgery, there is a high rate of complications and mortality. Therefore, as a minimally invasive alternative treatment, endogastric stent placement is gaining more and more attention.
2. Indications and contraindications.
It is mainly used for stenosis due to malignant tumors of the gastric sinus and duodenum and obstruction due to direct invasion or extraluminal compression of pancreatic and biliary tumors. The only absolute contraindication is perforation of the gastrointestinal tract.
3. Operation technique.
The operation should be performed in a room with X-ray fluoroscopy. Preoperative imaging to understand the anatomy of the lesion and the length and degree of stenosis will help the operation. Biliary obstruction often occurs in combination with gastric outlet-duodenal obstruction (especially in patients with pancreatic cancer) and often precedes gastric outlet obstruction. In patients with coexisting or impending biliary obstruction, the biliary stent should be placed before the duodenal stent is placed, because once the duodenal stent is placed it is difficult for the biliary stent to enter the bile duct through the papilla. For biliary obstruction that occurs after duodenal stent placement, a percutaneous, transhepatic route is often used.
The most commonly used intestinal stent for gastroduodenal use is Microvasive’s Wallstent, an uncoated metal stent available in 20 mm and 22 mm internal diameters with a 10 Fr diameter release system ranging from 160 cm to 255 cm in length. More recently, Boston Scientific has also introduced the intestinal stent WallFlex, a nickel-titanium alloy stent with a body diameter of 22 mm and a proximal umbrella diameter of 27 mm, available in 6 cm, 9 cm and 12 cm lengths. Both stents can be released through the clamp channel of a therapeutic endoscope.
The stents can be inserted in two ways: via endoscopic clamp tract release (TTS) and via guidewire release (OTW). Compared to the OTW approach, the TTS approach is more advantageous in that it allows for simultaneous release under both endoscopic and x-ray surveillance and accurate positioning. The lumen of the proximal stenosis can be identified more clearly under the endoscope, which makes it easy to complete the operation of the guidewire through the stenosis. Insertion of the stent pusher via the endoscopic clamp channel can effectively avoid the pusher from knotting in the wide gastric lumen during insertion. The operation is easy and fast.
4. Efficacy.
Most of the published data so far are derived from case reports and small-scale clinical trials. These data show that intestinal stenting has a similar success rate compared to surgical palliative surgery (approximately 90% of patients have improved clinical symptoms), but has a lower complication rate, operation-related mortality, and cost than surgical procedures. However, approximately 15% to 40% of patients require repeat endoscopic intervention due to recurrent symptoms or biliary obstruction. Newer ideas suggest that this problem can be addressed by using a laminated stent at the time of initial treatment to avoid re-infarction caused by tumor proliferation. A recently published systematic review compared gastro-jejunostomy and gastroduodenal stent placement. 307 cases by Hosono et al. showed a higher success rate of duodenal self-expanding metal stent treatment, a shorter time to initiation of feeding after operation, a lower incidence of complications, a lower incidence of delayed gastric emptying, and a shorter hospital stay compared to surgical gastro-jejunostomy, with no difference in 30-day mortality. differences. Another review reviewed 44 studies, but only two of them were randomized clinical trials. In these studies, a total of 1,046 patients were placed with duodenal stents, most of which were noncoated metal stents, while 297 patients underwent gastro-jejunostomy. The results showed a higher initial clinical success rate for stent placement (89%:72%), comparable rates of major complications for both (7%:6% for early stage and 18%:17% for late stage), and recurrent obstructive symptoms were more common in patients with stent placement. This result suggests that patients with shorter expected survival time are more suitable for stenting, while gastro-jejunostomy is more suitable for patients with better prognosis.
5. Treatment of colonic obstruction.
Colon obstruction is a life-threatening disease, and approximately 8% to 29% of colon cancer patients will develop obstruction. In addition, some other pelvic malignant tumors (such as prostate cancer, bladder cancer, ovarian cancer) sometimes also invade or externally press the intestinal wall to cause colon obstruction. Colonic obstruction due to colon cancer often requires emergency surgery. At the same time, due to the inability to perform adequate bowel preparation before surgery, stage I anastomosis is often not possible and colostomy is required, which significantly increases the mortality rate, hospital stay and cost compared with patients undergoing elective surgery. With the use of intestinal stents in clinical practice, we have a new alternative to emergency surgery that allows patients to not only decompress and cleanse the bowel before surgery, but also makes phase I anastomosis possible.
6. Indications.
The indications for colonic stenting include.
(1) For colon cancer that can be resected radically, as a preoperative preparation instead of colostomy in case of intestinal obstruction.
(2) For unresectable advanced colon cancer as a means of palliative care.
(3) For colon obstruction due to metastatic cancer or external pressure lesions.
(4) Overlying stents are used for colonic vesicovaginal fistula, endocolonic fistula or colovaginal fistula.
(5) The use of colonic stents in colonic obstruction due to benign lesions is still controversial.
7. Operation technique.
The basic operation method is the same as the treatment of gastric outlet-duodenal obstruction. In addition to the above-mentioned advantages, the application of the TTS approach for colonic stent placement also helps to complete the treatment of malignant obstruction in the proximal colon (above the transverse colon), which is difficult to accomplish with the OTW approach (the OTW approach is often limited to the left hemicolectomy). The author successfully completed stent placement in two cases of malignant obstruction located in the hepatic flexure of the colon and ascending colon using the TTS approach with good results.
8. Efficacy.
Data on the efficacy of colonic stents for the treatment of colonic obstruction are mainly from a few case reports and small controlled trials. A recently published systematic review reviewed the results of 88 studies and concluded the following.
(1) The median operative success rate was 96% (ranging from 66% to 100%).
(2) The median clinical success rate was 92% (ranging from 46% to 100%).
(3) The success rate did not vary significantly regardless of the indication for stent placement (palliation or preoperative transition) and the etiology of the obstruction (primary/recurrent colon cancer, tumor infiltration from other sites, or external pressure).
(4) Fourteen of these studies reported the time to stent maintenance patency, with a median time of 106 days (68 to 288 days).
(5) The median rate of stent displacement was 1 1 % (0% to 50%).
(6) The median perforation rate was 45% (0% to 83%).
(7) The median rate of re-infarction was 12% (1% to 92%).
(8) Other complications (e.g., bleeding, abdominal pain, posterior urgency) are rare and usually not serious.
A small non-randomized controlled trial showed no advantage of overlapping stents over non-overlapping stents for relief of obstructive symptoms in the absence of fistulae. Although overlapping stents theoretically reduce the risk of tumor growth into the stent, they are also more likely to migrate.