COMMENTARY

Implantable Self-expanding Metal Stents for Malignant Colonic Obstruction

David A. Johnson, MD, FACG, FACP

Disclosures

January 11, 2008

Ultraflex precision Colonic Stent Placement for Palliation of Malignant Colonic Obstruction: A Prospective Multicenter Study

Repici A, Fregonese D, Costamanga G, et al
Gastrointest Endosc. 2007;66:920-927

Abstract

Comparison of Uncovered Stent With Covered Stent for Treatment of Malignant Colorectal Obstruction

Lee KM, Shin SJ, Hwang JC, et al
Gastrointest Endosc. 2007;66:931-936

Editor's Note: Dr. Johnson's summary and commentary collaboratively address these 2 reports on colonic stent placement for palliation of malignant colonic obstruction

Summary

Colorectal cancer is one of the most prevalent malignancies in the world. Unfortunately, colonic obstruction is usually a late stage of presentation of this disease and is more typical of an advanced and noncurable lesion. A palliative approach is standard in these patients, the intent being to relieve the obstruction and thereby treat the obstructive symptoms (abdominal pain, vomiting, bloating) and to avoid a perforation that might precipitously threaten the patient's life. Surgical therapy has been the standard approach in this setting, with patients generally undergoing a temporary or permanent colostomy. The surgical approach, however, is associated with significant risk and morbidity. Typically, these patients are not optimal surgical candidates due to the advanced stage of the tumor and the associated poor nutritional status.

In addition to surgical strategies for the relief of colon cancer obstruction, a variety of endoscopic interventions have been tried. These include palliative dilation and ablative techniques (using laser or argon-plasma coagulation). These approaches, however, have been associated with increased risk for perforation as well as rapid recurrence of obstruction. The use of implantable self-expanding metal stents is the focus of evaluation in the articles by Repici and colleagues and Lee and colleagues.

In the first study by Repici and colleagues, 44 patients with malignant colonic obstruction were prospectively evaluated following the placement of nitinol self-expanding metal stents (SEMS). Procedures were performed under fluoroscopic (and, optionally, endoscopic) visualization. In all cases, a stent was selected to provide a 1-cm extension beyond the proximal and distal end of the stricture margins. When needed, dilation was performed prior to stent placement with either balloon or bougienage (Savary) dilators. A second stent was necessary in 5 patients, 3 because of underestimation of the stricture length, and 2 because of deployment error. Overall, technical success was achieved in 95% of patients, with survival rates at 6 months of 67% (95% confidence interval [CI], 54%-84%). None of the deaths were stent-related.

In the second report by Lee and colleagues, 80 patients with malignant colonic obstruction were followed prospectively in a nonrandomized single-center study comparing the outcome with uncovered vs covered SEMS. Technical success was 100% in both groups, and the clinical success rates was equivalent (95.1% for uncovered SEMS vs 97.4% for covered SEMS). Although there was no difference in early migration of SEMS, late stent migration was more common in the covered stent group (0% vs 40%, respectively; P = .005). Additionally, later (more than 1 week after placement) loss of stent function was more frequent with covered SEMS than with uncovered SEMS (18.8% vs 60%, respectively). There was no statistically significant difference in tumor ingrowth between the 2 groups, although there were only 3 such patients in the uncovered SEMS group and none in the covered SEMS group.

Viewpoint

Both of these studies demonstrate the technical success of SEMS placement for malignant strictures of the colon. The over-the-wire delivery systems can accommodate the 30-mm maximum flared diameter of the SEMS. The delivery of the through-the-scope colonic SEMS is currently restricted to the smaller diameters (20-22 mm). Although not studied in a comparative way, it makes sense that larger SEMS diameters should provide more relief and long-term durability in optimizing the patency of the stricture. The second study, while not randomized, suggests that in the colon, there may not be a need for covered SEMS. This issue is moot at present in the United States, where covered colonic SEMS are not available. Tumor ingrowth remains the primary reason why covered SEMS are used in the upper gastrointestinal tract. The lack of a difference between the 2 treatment groups in this regard in this study should be considered a potential type I error considering the relatively small number of patients with this occurrence.

Given the technical success achieved with SEMS and the known morbidity and risks associated with surgical approaches, it seems that this option should be considered preferable to surgical diversion intervention. We recognize anatomic locations that represent technical limitations and which will preclude SEMS placement (specifically, the distal rectum, cecum, and ascending colon adjacent to the ileocecal valve). The use of SEMS in the colon will likely increase, particularly for patients with noncurable obstructive colon cancer and those who are poor surgical candidates and with left-sided disease.

Abstract

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