Expandable metal stents for malignant colorectal strictures

Controversies of colonic stenting in obstructive left colorectal cancer: a critical analysis with meta-analysis and meta-regression

PURPOSE

After almost three decades since the first description of colonic stents, the controversies of its safe application continue to impede the readiness of adoption by clinicians for malignant left bowel obstruction. This review seeks to address some of the controversial aspects of stenting and its impact on surgical and oncological outcomes.

METHODS

Medline, Embase, and CNKI were searched for articles employing SEMS for left colonic obstruction. Outcomes analyzed include success rates, complications, and long-term survival. Pooled risk ratio (RR) and 95% confidence interval (CI) were estimated.

RESULTS

36 studies were included with 2002 patients across seven randomized controlled trials and 29 observational studies. High technical (92%) and clinical (82%) success rates, and low rates of complications, including perforation (5%), were found. Those with > 8% perforation rates had poorer technical success rates than those with ≤ 8%, but there were no significant differences in 90-day in-hospital mortality and three and 5-year overall and disease-free survival. A significant increase was found in technical (RR = 1.094; CI, 1.041-1.149; p < 0.001) and clinical (RR = 1.158; CI, 1.064-1.259; p = 0.001) success rates when the duration between stenting and surgery was ≥ 2 weeks compared to < 2 weeks, but there were no significant differences in perforation rates, 90-day in-hospital mortality, and long-term survival.

CONCLUSIONS

Colonic stenting is safe and effective with high success rates and low complication rates. However, outcomes of higher perforation rates and optimal timing from stent till surgery remain unclear, with only a few studies reporting on these outcomes, leaving areas for future research.

Biopsy sampling during self-expandable metallic stent placement in acute malignant colorectal obstruction: a narrative review

BACKGROUND

Histopathology is a crucial part of diagnosis and treatment guidance of colorectal cancer. In Denmark, it is not routine to biopsy during self-expandable metallic stent (SEMS) placement as a treatment option for acute colorectal obstruction of unknown etiology. This is due to lack of knowledge about the risks of hemorrhage, and thus the risk to aggravate the deteriorating overview conditions. Therefore, the aim of this study is to investigate whether there is evidence to avoid biopsy sampling during acute SEMS placement.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched for relevant studies. Studies were included if they described biopsy sampling in relation to SEMS placement. Additionally, national and international guidelines were scrutinized on Google and by visiting the websites of national and international gastrointestinal societies.

RESULTS

In total, 43 studies were included in the review. Among these, one recommended biopsy during SEMS placement, three advised against biopsy, 23 just reported biopsy was performed during the procedure, and 16 reported biopsy before or after the procedure, or the timing was not specified. Among the 12 included guidelines, only two described biopsy during SEMS placement.

CONCLUSION

The literature on the subject is limited. In 24 of the 43 included studies, biopsy sampling was done during SEMS placement without reporting a decrease in the technical success rate. The included guidelines were characterized by a general lack of description of whether biopsy during SEMS placement should be performed or not. Prospective studies are needed in order to establish the real risk of hemorrhage, if any, when a biopsy is obtained.

Endoscopic stenting in colorectal cancer

Acute malignant large bowel obstruction presents as one of the few emergencies of colorectal cancer (CRC). Management of this condition can either be by (I) upfront surgery or (II) the use of self-expanding metallic stent (SEMS) as a bridge to elective surgery. For patients with metastasis, the use of SEMS is reported to enable earlier commencement of chemotherapy. Although the use of SEMS in patients with acute malignant large bowel obstruction looks promising, it is plagued by its own set of complications and divided opinion over its long-term outcomes. Conflicting data are present, and definitive indication requires further evaluation and debate. This article will describe the typical presentation of patients with acute malignant large bowel obstruction. An introduction to the SEMS insertion procedural steps will be undertaken. Following which the article aims to review the safety profile of SEMS and the short- and long-term outcomes of SEMS in both the curative and palliative setting.

Colonic stents for malignant bowel obstruction: current status and future prospects

Introduction: Although more than two decades are already passed from the first description of this technique, the debate remains open on the role of self-expanding metal stents (SEMS) placement in the management of malignant bowel obstruction (MBO). According to most recent data, SEMS placement is considered a safe and effective alternative treatment as a bridge to surgery(BTS). In addition, stent placement should be considered as primary option for palliative treatment of obstructing cancer.Areas covered: Current status, indication, technique, oncological outcomes, advantages, and risks of SEMS placement in MBO were reviewed.Expert commentary: The placement of colonic SEMS for palliation and for BTS in patients with MBO has been increasingly reported and it seems to have several advantages over emergency surgery. Substantial concerns of tumor seeding following SEMS placement, especially in case of perforation, have been raised in numerous studies. Actually, no significant differences are reported in oncologic long-term survival between patients undergoing stent placement as a BTS and those undergoing emergency surgery. Considering all the mentioned factors, indication for colorectal stenting should be evaluated only in highly specialized centers, in the context of multidisciplinary approach where risks and benefits of stenting are carefully weighed, especially in the BTS setting.

Obstruction is associated with perineural invasion in T3/T4 colon cancer

AIM

Perineural invasion (PNI) is a risk factor for recurrence and metastasis and consequently leads to decreased survival in patients with various malignancies. Recent studies showed that stent placement in obstructive colon cancer increases the frequency of PNI. We hypothesized that mechanical stress including obstruction itself may be associated with PNI.

METHOD

We retrospectively reviewed 496 patients with pathological T3 or T4 colon cancer who did not receive preoperative treatment. Data were collected from medical charts and pathological findings. The relationships between PNI and other clinicopathological factors were analysed using univariate and multivariate analyses.

RESULTS

PNI was observed in 239 (48%) patients. Obstruction was markedly more frequent in PNI-positive cancer (39%) than in PNI-negative cancer (24%, P = 0.0003). Multivariate analyses identified obstruction as one of the significant factors associated with PNI (OR 1.68, P = 0.028). Moreover, in 414 patients without distant metastasis who underwent complete resection, PNI was an independent factor associated with poor recurrence-free survival (hazard ratio 2.35, P = 0.003). The coexistence of PNI and obstruction resulted in greater decreases in recurrence-free survival than PNI-negative and/or non-obstructive cases.

CONCLUSION

Our results suggest that obstruction is associated with PNI and consequently contributes to an increased postoperative recurrence in colon cancer.

Using stents in the management of malignant bowel obstruction: the current situation and future progress

The use of self-expanding metal stents (SEMS) has been considered an effective and safe alternative to emergency surgery as bridge to surgery or for palliation in advanced colorectal cancer even though more recent data have raised concerns on both early and long-term outcomes when patients are treated with bridge to surgery indications. Areas covered: A comprehensive literature review of articles on endoscopic management of malignant bowel obstruction was performed. Indication, technique, outcomes, benefits and risks of these treatments in acute malignant colonic obstruction were reviewed. The clinical effectiveness and safety of SEMS in obstructive colorectal cancer, as bridge to surgery or for palliation compared to surgery, is discussed. Expert commentary: SEMS placement, when performed in tertiary level center with appropriate expertise in colorectal stenting, may have several advantages over surgery avoiding the potential for surgical morbidity in a typically frail group of patients even though these advantages are to be carefully balanced over the risk of life-threatening, stent-related complications.

Interventional Therapy of Esophageal Cancer

Esophageal cancer (EC) is the fourth leading cause of cancer death in China. Despite a lot of advances in diagnosis and therapy, the survival rate of patients with EC is low. There is urgent need for a variety of methods and techniques to improve the survival time and alleviate the lesions of EC. Nowadays, alternative and less invasive approaches to the treatment of ECs are being identified. Here, we review several main interventional methods at different stages of EC, including endoscopic resection, stent placement, arterial infusion, photodynamic therapy, and radiofrequency ablation. This review will focus on the indications, methods, clinical outcomes, and complications of these methods, which may help guide the way forward.

Socioeconomic Inequalities in the Utilization of Colorectal Stents for the Treatment of Malignant Bowel Obstruction

BACKGROUND

Colorectal stents are increasingly employed as a bridge to surgery or for palliative relief of malignant large bowel obstruction.

AIM

To explore determinants of inpatient colorectal stent utilization (CRSU).

METHODS

An analysis of the 2012 National Inpatient Sample was performed. International Classification of Diseases, 9th revision, codes were used to identify discharges associated with CRSU and patient/hospital factors for inclusion in a logistic regression model.

RESULTS

We identified 217,055 inpatient colonoscopies, approximating 1.1 million inpatient colonoscopies nationwide. Colorectal stents were placed in 1.4 % of all procedures. Across all racial groups, Medicare was the most common payer. Patients with commercial insurance had lower CRSU compared with Medicare patients [adjusted odds ratio (OR) 0.83, 95 % confidence interval (CI) 0.75-0.92]. No gender disparities were identified (OR 0.96, 95 % CI 0.89-1.03). In addition, no racial differences in CRSU existed between Caucasians versus African-Americans (OR 0.94, 95 % CI 0.83-1.06) and Caucasians versus Hispanics (OR 0.96, 95 % CI 0.83-1.1). Compared with patients living in less affluent neighborhoods, those residing in more affluent areas had higher CRSU (OR 1.65, 95 % CI 1.46-1.86). This displayed a linear relationship with the odds of CRSU increasing as household income increased. Less affluent patients also had the highest total charges and longest wait time to CRSU. CRSU was highest among patients treated in larger medical centers (OR 1.7, 95 % CI 1.51-1.93) and teaching hospitals (OR 3.9, 95 % CI 3.2-4.8).

CONCLUSION

Individuals from less affluent neighborhoods have lower colorectal stent utilization. This disparity is independent of race and likely related to poorer access to healthcare resources.

Stents for colorectal obstruction: Past, present, and future

Since the development of uncovered self-expanding metal stents (SEMS) in the 1990s, endoscopic stents have evolved dramatically. Application of new materials and new designs has expanded the indications for enteral SEMS. At present, enteral stents are considered the first-line modality for palliative care, and numerous types of enteral stents are under development for extended clinical usage, beyond a merely palliative purpose. Herein, we will discuss the current status and the future development of lower enteral stents.

A Novel Foam Contrast Agent Suitable for Fluoroscopic Interventional Procedure: Comparative Study of Physical Properties and Experimental Intervention in Animal Model

In fluoroscopic contrast study for interventional procedure, liquid contrast agent may be diluted in body fluid, losing its contrast effect. We developed a novel contrast agent of “foam state” to maintain contrast effect for enough time and performed a comparative study of physical properties and its usefulness in experimental intervention in animal model. The mean size of microbubble of foam contrast was 13.8 ± 3.6 µm. The viscosity was 201.0 ± 0.624 cP (centipoise) and the specific gravity was 0.616. The foam decayed slowly and it had 97.5 minutes of half-life. In terms of the sustainability in a slow flow environment, foam contrast washed out much more slowly than a conventional contrast. In experimental colonic stent placement, foam contrast revealed significantly better results than conventional contrast in procedure time, total amount of contrast usage, and the number of injections (p < 0.05). Our foam contrast has high viscosity and low specific gravity and maintains foam state for a sufficient time. Foam contrast with these properties was useful in experimental intervention in animal model. We anticipate that foam contrast may be applied to various kinds of interventional procedures.

Metallic stent insertion with double-balloon endoscopy for malignant afferent loop obstruction

Progress in double-balloon endoscopy (DBE) has allowed for the diagnosis and treatment of disease in the postoperative bowel. For example, a short DBE, which has a 2.8 mm working channel and 152 cm working length, is useful for endoscopic retrograde cholangiopancreatography in bowel disease patients. However, afferent loop and Roux-limb obstruction, though rare, is caused by postoperative recurrence of biliary tract cancer with intractable complications. Most of the clinical findings involving these complications are relatively nonspecific and include abdominal pain, nausea, vomiting, fever, and obstructive jaundice. Treatments by surgery, percutaneous transhepatic biliary drainage, percutaneous enteral stent insertion, and endoscopic therapy have been reported. The general conditions of patients with these complications are poor due to cancer progression; therefore, a less invasive treatment is better. We report on the usefulness of metallic stent insertion using an overtube for afferent loop and Roux-limb obstruction caused by postoperative recurrence of biliary tract cancer under short DBE in two patients with complexly reconstructed intestines.

Enteral stents for the management of malignant colorectal obstruction

Colorectal cancer (CRC) is the 3^rd most common cancer in the United States with more than 10000 new cases diagnosed annually. Approximately 20% of patients with CRC will have distant metastasis at time of diagnosis, making them poor candidates for primary surgical resection. Similarly, 8%-25% of patients with CRC will present with bowel obstruction and will require palliative therapy. Emergent surgical decompression has a high mortality and morbidity, and often leads to a colostomy which impairs the patient’s quality of life. In the last decade, there has been an increasing use of colonic stents for palliative therapy to relieve malignant colonic obstruction. Colonic stents have been shown to be effective and safe to treat obstruction from CRC, and are now the therapy of choice in this scenario. In the setting of an acute bowel obstruction in patients with potentially resectable colon cancer, stents may be used to delay surgery and thus allow for decompression, adequate bowel preparation, and optimization of the patient’s condition for curative surgical intervention. An overall complication rate (major and minor) of up to 25% has been associated with the procedure. Long term failure of stents may result from stent migration and tumor ingrowth. In the majority of cases, repeat stenting or surgical intervention can successfully overcome these adverse effects.

Colorectal stenting vs ileus tube drainage for treatment of acute malignant colorectal obstruction

AIM: To compare the effect of endoscopic colorectal stenting vs ileus tube drainage for treatment of acute malignant colorectal obstruction.

METHODS: With the aid of fluoroscopy, 45 patients with acute malignant colorectal obstruction were treated by endoscopic colorectal stenting (n = 27) or ileus tube drainage (n = 18). Postoperative remission and complications were compared between the two groups.

RESULTS: The technical success rate of colorectal stenting was 96.3%, and that of ileus tube drainage was 100%. Relief of symptoms occurred within 1-4 d. Thirty-eight patients underwent subsequent elective surgical resection 6-8 d after obstruction relief, without complications of anastomotic leakage or intraperitoneal infection.

CONCLUSION: Preoperative stenting and ileus tube drainage in acute colonical obstruction can effectively relieve obstruction and improve the quality of life, although each has its own advantages and disadvantages.

Perforation in colorectal stenting: a meta-analysis and a search for risk factors

BACKGROUND

Recent studies suggest that there is a substantial risk of perforation after colorectal stent placement.

OBJECTIVE

To identify risk factors for perforation from colonic stenting.

DESIGN

A meta-analysis of 86 studies published between 2005 and 2011.

SETTING

Multicenter review.

PATIENTS

All patients who underwent colorectal stent placement.

INTERVENTION

Colorectal stent placement.

MAIN OUTCOME MEASUREMENTS

The occurrence of perforation with subgroup analyses for stent design, stricture etiology, stricture dilation, and concomitant chemotherapy, including the use of bevacizumab.

RESULTS

A total of 4086 patients underwent colorectal stent placement; perforation occurred in 207. Meta-analysis revealed an overall perforation rate of 7.4%. Of the 9 most frequently used stent types, the WallFlex, the Comvi, and the Niti-S D-type had a higher perforation rate (>10%). A lower perforation rate (<5%) was found for the Hanarostent and the Niti-S covered stent. Stenting benign strictures was associated with a significantly increased perforation rate of 18.4% compared with 7.5% for malignant strictures. Dilation did not increase the risk of perforation: 8.5% versus 8.5% without dilation. The subgroup of post-stent placement dilation had a significantly increased perforation risk of 20.4%. With a perforation rate of 12.5%, bevacizumab-based therapy was identified as a risk factor for perforation, whereas the risk for chemotherapy without bevacizumab was 7.0% and not increased compared with the group without concomitant therapies during stent therapy (9.0%).

LIMITATIONS

Heterogeneity; a considerable proportion of data is unavailable for subgroup analysis.

CONCLUSIONS

The perforation rate of colonic stenting is 7.4%. Stent design, benign etiology, and bevacizumab were identified as risk factors for perforation. Intraprocedural stricture dilation and concomitant chemotherapy were not associated with an increased risk of perforation.

A novel animal model of gastrointestinal obstruction for the development of stent

BACKGROUND

The need for newer gastrointestinal (GI) stents has been continuously raised. Newly developed stents are generally tested for physical properties in vitro and directly introduced to clinical practice because there is no reliable animal model of GI obstruction. The aim of this study was to establish an animal model both that can represent obstruction of the GI tract and be used to develop new stents.

MATERIAL AND METHODS

Surgical obstruction of the descending colon by wrapping with a nonabsorbable synthetic mesh and rubber bands was made in 17 healthy mongrel dogs. Four days later, a covered self-expanding metallic stent was placed for the obstructed segment in each dog under fluoroscopic guidance. Patency and migration of the inserted stents were evaluated clinically on a daily basis and fluoroscopically on a weekly basis. After sacrifice of the dogs, the degree and extent of residual colonic obstruction were assessed fluoroscopically. The specimen of the colonic obstructed segment was examined microscopically.

RESULTS

In all 17 mongrel dogs, segmental obstruction in the descending colon was successfully created and confirmed with fluoroscopic examination using a contrast medium. The percentage of luminal narrowing ranged from 99%-100%. Stent placement was technically successful in all 17 dogs. During the follow-up period, stent migration occurred in 12 dogs and indwelling time of a stent ranged from 0-95 d (mean 29.2 ± 38.8 d). On postmortem pathologic examination, it was found that fibrosis had newly formed outside the colonic longitudinal muscle layer in all dogs.

CONCLUSIONS

Our canine colonic obstruction model is the first animal model that can be feasible for developing a new design of stent and provide in vivo data on complications, particularly stent migration.

Evidence-based recommendations on colorectal stenting: a report from the stent study group of the korean society of gastrointestinal endoscopy

Recently, placement of self-expandable metallic stents has been used for the treatment of colorectal obstruction. As domestic awareness of colorectal cancer has increased, the number of colorectal stenting procedures performed has also increased. We aimed to provide evidence-based recommendations for colorectal stenting to aid gastroenterologists in making informed decisions regarding the management of patients who present with colorectal obstruction. The working group consisted of eight gastroenterologists who actively practice and conduct research in the field of colorectal stenting and are the members of the Stent Study Group of the Korean Society of Gastrointestinal Endoscopy. A literature search was conducted using the PubMed, Embase, KoreaMed, and the Cochrane Library databases to identify relevant articles published between January 2001 and June 2012. Based on the modified Delphi process, 10 recommendation statements regarding indications, usefulness, methodology and complications of colorectal stenting, and alternative treatments for malignant colorectal obstruction were determined. The contents will be widely distributed, and periodically revised to reflect the latest knowledge. These evidence-based recommendations for colorectal stenting will provide gastroenterologists and patients with appropriate and balanced information, and will improve the quality of care.