Palliative self-expandable metallic stent placement for colorectal obstruction caused by an extracolonic malignancy

Abstract

Introduction

Acute colorectal obstruction causes symptoms such as nausea, vomiting, abdominal pain, distention, and altered bowel habits, and results in bowel dilation and fluid retention. Perfusion to the intestine can be compromised, leading to necrosis, dehydration, or perforation—complications that increase the mortality rate. Malignancy is the most common cause of colorectal obstruction, causing 90% of cases.1 Malignant colorectal obstruction (MCRO) generally requires rapid bowel decompression, such as emergency surgery, which is associated with high mortality and morbidity.2,3

Since its introduction for treating MCRO in 1991,4 endoscopic stenting with self-expandable metallic stents (SEMSs) has become widely accepted for the palliative management of malignant colonic obstruction and as a bridge to surgery.5–8 Given its low invasiveness, this procedure is an option, along with bypass surgery or colostomy, for patients with unresectable colonic obstructions.9

MCRO can also occur in patients with an extracolonic malignancy (ECM), such as gastric, pancreatobiliary, urogenital, and gynecologic malignancies.10,11 Accumulated evidence has shown that SEMS placement is an acceptable alternative to surgery for managing MCRO caused by colorectal cancer (CRC). Although the obstructions in CRC are caused by intraluminal growth, those in ECM occur as a result of peritoneal dissemination, direct invasion from an organ near the colon into the lumen, or extrinsic compression. The tumor fixes the stricture site, which loses its flexibility. In addition, intestinal peristalsis can be blocked by adhesions after a previous operation, radiation, or carcinomatosis from the primary lesion. These conditions make it difficult to insert a colonoscope, to traverse the stricture, and to insert the SEMS. In comparison with CRC, bowel obstruction caused by ECM tends to cause a complex stricture, potentially at more than one location. Therefore, accessing or traversing a stricture caused by ECM is more difficult than for those resulting from CRC.

Emergency surgery performed on acutely ill patients with large-bowel obstruction due to malignancy, which includes bypasses, resection, and colostomy, has a 16–23% morbidity rate and a 5–20% mortality rate.12–14 Palliative surgery for MCRO caused by ECM is also associated with significant morbidity.15,16 Even with successful surgery, many patients require a colostomy or ileostomy. The stoma has significant morbidity and reduces the quality of life over the short- and long-term.17 Given the low invasiveness of SEMS placement, it is an effective alternative for resolving MCRO caused by ECM.

Until 2000, few patients with colorectal obstruction due to ECM had undergone SEMS placement for palliation.14,18 In most of these early studies, colonic obstruction from ECM was included in malignant colonic obstruction and was not distinguished from that of CRC. Recently, more articles on this specific procedure have been published with advances in endoscopic techniques and SEMS technology.10,19–33 Ten years have passed since a pooled analysis reported that the technical failure rate was higher in patients with ECM versus primary CRC5; to date, the availability and safety of this procedure have not been determined sufficiently.

This paper reviews the treatment for MCRO caused by ECM, with emphasis on SEMS placement.

Indications and practical considerations

As with CRC, SEMS placement is contraindicated in patients with enteral ischemia, suspected or impending perforation, multiple small-bowel site involvement, other synchronous colonic obstruction, or intra-abdominal abscess/perforation.

Typically, acute colonic obstruction is symptomatic. Abdominal x-rays show a dilated colon and colonoscopy shows an obstruction caused by an intra- or extraluminal lesion. To evaluate the cause and location of the obstruction, computed tomography (CT) with/without a contrast agent, colonoscopy, and barium enema or enema with water-soluble contrast material could be performed. Kim et al32 reported that CT combined with a barium enema was useful for evaluating the number and length of strictures. Magnetic resonance imaging is also useful for ruling out a fistula between the intestine and uterus or bladder.

The obstruction with an ECM often involves the left colon or rectum (Table 1). Although it can be more difficult to insert a SEMS for an obstruction proximal to the splenic flexure,34 recent articles report the effectiveness and safety of SEMS placement for a proximal obstruction in ECM.26,30,33 Improvements in endoscopy, guidewires, and stents have increased the indications for treating proximal obstructions of the colon caused by an ECM.

Although multiple strictures typically rule out SEMS placement, some authors have reported simultaneous SEMS placement at two different obstruction sites.10,22,26,32 Kim et al30 reported better clinical outcomes for SEMS placement for patients with one or two obstructions versus multiple obstructions. After a careful pre-procedural examination, including high-resolution CT, barium, or water-soluble enema images, we think one can insert a SEMS for one or two obstructions.

The etiology of ECM includes metastases and carcinomatosis from gastrointestinal, pancreatobiliary, urogenital, and gynecological malignancies. It is not clear whether it includes recurrent CRC. Some authors report SEMS placement for EMC that includes recurrent CRC.19,35 It seems reasonable to include it when CT identifies disseminated or recurrent CRC as the cause of the obstruction resulting from extraluminal compression. Kim et al30 found that SEMS placement was less effective than emergency surgery for palliation of colorectal obstruction in patients with advanced gastric cancer, although there are differences based on the primary disease, dominant pattern of obstruction (e.g., extrinsic compression, adhesion, or tumor infiltration), or location of obstruction (e.g., upper abdominal cavity or pelvic cavity).

In some cases, MCRO due to ECM did not improve after colonic stenting. Those patients had multiple stenoses, intestinal stenosis, impaired bowel movement, or impaired digestive tract motility due to an omental cake. The patient and tumor status should be evaluated carefully before deciding to stent a MCRO due to ECM.

SEMS placement procedures

Complications

The most common complication is reobstruction of the SEMS due to tumor ingrowth (Table 2). This complication can be resolved by placing an additional SEMS using stent-in-stent techniques or by surgery. Given the etiology of ECM, obstruction at another site can also occur. When obstruction symptoms recur, the possible causes of the patient’s symptoms must be reassessed using CT or a barium or water-soluble enema. Although secondary stent-in-stent SEMS placement for MCRO is a promising way to resolve the symptoms,39 it is reasonable to perform this procedure in patients who are not candidates for surgery. The use of a covered SEMS is not favored as first-line therapy because of the high rate of migration. For secondary intervention for an occluded SEMS due to tumor ingrowth, however, a covered SEMS is a promising option for managing tumor invasion via the stent mesh. In such situations, the risk of migration is relatively low.

Sometimes, the SEMS becomes kinked and does not dilate in an acutely angled portion of the bowel, such as the splenic or hepatic flexure (Fig. 1). This complication can occur with a braided-type SEMS, such as the WALLSTENT, but not with a knitted-type SEMS, such as the Niti-S. We can manage this situation with balloon dilation or additional stent-in-stent placement.

Figure 1

Endoscopic balloon dilation after WallFlexTM Colonic Stent (made by Boston Scientific Corporation (Natick, MA 01760-1537)) placement with insufficient expansion.

Stent migration was the second most common complication. In general, migration is caused by misplacement, inadequate stent length, placement for incomplete obstruction, or soft tumor tissue. Late stent migration might be related to tumor shrinkage caused by chemotherapy after SEMS placement. A covered SEMS is regarded as superior at preventing tumor ingrowth, but inferior at preventing stent migration in MCRO, because the stent is less embedded in the lumen wall compared with uncovered stents.40 Because the ECM obstruction is caused by both direct tumor invasion and extrinsic compression, adhesions, and decreased peristalsis, it is assumed that the migration rate of SEMS placed for ECM is high, although no prospective, randomized study has examined this issue.

Article information

References