CT colonography after metallic stent placement for acute malignant colonic obstruction

Detection methods of synchronous colorectal lesions in proximal colon for patients with obstructive colorectal cancer: a literature review

INTRODUCTION

Colorectal cancer holds a high morbidity and mortality rate. As a common method for colorectal cancer detection, colonoscopy has difficulty in passing through the malignant stenosis in patients with obstructive colorectal cancer, which results in incomplete detection and missed diagnosis. The missed synchronous lesions increase the risk of metachronous cancer. Therefore, detecting proximal synchronous lesions in patients with obstructive colorectal cancer should be appreciated before operation.

AREA COVERED

This review evaluates related literature, aiming at providing clinicians with more ideas and attention for detecting proximal synchronous lesions in patients with obstructive colorectal cancer.

EXPERT OPINION

In patients with obstructive colorectal cancer, missed diagnosis of lesions proximal to the obstruction may lead to metachronous colorectal cancer. Except for preoperative colonoscopy which is difficult to pass through malignant stenosis, other methods that can evaluate proximal colon segment are critical. This article introduced several preoperative, intraoperative and postoperative measures for synchronous lesions detection. The choice of methods should base on patients' conditions, aiming at a high diagnostic yield and low risk. Early detection and resection of synchronous lesions in the proximal section of malignant obstruction are expected to minimize the risk of metachronous colorectal cancer and even effect follow-up treatment strategy, which deserves the attention of clinicians.

Comparison of colonic stents, stomas and resection for obstructive left colon cancer: a meta-analysis

BACKGROUND

Emergency surgery (ES) is the standard-of-care for left-sided obstructing colon cancer, with self-expanding metallic stents (SEMSs) and diverting colostomies (DCs) being alternative approaches. The aim of this study was to review the short- and long-term outcomes of SEMS versus ES or DC.

METHODS

Embase and Medline were searched for articles comparing SEMS versus ES or DC. Primary outcomes were survival and recurrence rates. Secondary outcomes were peri- and postoperative outcomes. SEMS-specific outcomes include success and complication rates. Pooled odds ratio and 95% confidence interval were estimated with DerSimonian and Laird random effects used to account for heterogeneity.

RESULTS

Thirty-three studies were included, involving 15,224 patients in 8 randomized controlled trials and 25 observational studies. There were high technical and clinical success rates for SEMS, with low rates of complications. Our meta-analysis revealed increased odds of laparoscopic surgery and anastomosis, and decreased stoma creation with SEMS compared to ES. SEMS led to fewer complications, including anastomotic leak, wound infection, ileus, myocardial infarction, and improved 90-day in-hospital mortality. There were no significant differences in 3- and 5-year overall, cancer-specific and disease-free survival. SEMS, compared to DC, led to decreased rates of stoma creation, higher rates of ileus and reoperation, and led to longer hospital stay.

CONCLUSIONS

SEMS leads to better short-term outcomes but confers no survival advantage over ES. It is unclear whether SEMS has better short-term outcomes compared to DC. There is a lack of randomized trials with long-term outcomes for SEMS versus DC, hence results should be interpreted with caution.

Endoscopic stenting of malignant, benign and iatrogenic colorectal disorders: a primer for radiologists

In recent years, endoscopic placement of intraluminal stents is increasingly used to manage a widening range of colorectal disorders. Self-expanding metal stents represent an established alternative to surgery for the palliation of unresectable carcinomas and currently allow a "bridge-to-surgery" strategy to relieve large bowel obstruction and optimise the patients' clinical conditions before elective oncologic resection. Additionally, intraluminal stents represent an appealing option to manage obstructing extracolonic tumours and selected patients with benign conditions such as refractory anastomotic strictures and post-surgical leaks.This educational paper reviews the technical features and current indications of colorectal stenting and presents the expected and abnormal radiographic, CT and MRI appearances observed during the endoscopic management of malignant, benign and iatrogenic colonic disorders with stents. The aim is to provide radiologists with a thorough familiarity with stent-related issues, which is crucial for appropriate reconstruction of focused CT images, correct interpretation of early post-procedural studies and elucidation of stent-related complications such as misplacement, haemorrhage, perforation, migration and re-obstruction.

Synchronous colorectal cancer using CT colonography vs. other means: a systematic review and meta-analysis

OBJECTIVES

The objective of our study was to systematically review the evidence about synchronous colorectal cancer diagnosed with or without computed tomography colonography (CTC).

MATERIALS AND METHODS

Two systematic searches were performed (PubMed and EMBASE) for studies reporting the prevalence of synchronous colorectal cancer (CRC): one considering patients who underwent CTC and the another one considering patients who did not undergo CTC. A three-level analysis was performed to determine the prevalence of patients with synchronous CRC in both groups of studies. Heterogeneity was explored for multiple variables. Pooled prevalence and 95% confidence interval (CI) were calculated. A quality assessment (STROBE) was done for the studies.

RESULTS

For CTC studies, among 2645 articles initially found, 21 including 1673 patients, published from 1997 to 2018, met the inclusion criteria. For non-CTC studies, among 6192 articles initially found, 27 including 111,873 patients published from 1974 to 2015 met the inclusion criteria. The pooled synchronous CRC prevalence was 5.7% (95% CI 4.7%-7.1%) for CTC studies, and 3.9% (95% CI 3.3%-4.4%) for non-CTC studies, with a significant difference (p = 0.004). A low heterogeneity was found for the CTC group (I² = 10.3%), whereas a high heterogeneity was found in the non-CTC group of studies (I² = 93.5%), and no significant explanatory variables were found. Of the 22 STROBE items, a mean of 18 (82%) was fulfilled by CTC studies, and a mean of 16 (73%) by non-CTC studies.

CONCLUSIONS

The prevalence of synchronous CRC was about 4-6%. The introduction of CTC is associated with a significant increase of the prevalence of synchronous CRCs.

Elective Surgery After Endoscopic Self-Expandable Metallic Stent Placement for Patients With Obstructive Colon Cancer: Preoperative Systemic Evaluation and Management

One-stage curative surgical resection for obstructive colon cancer is challenging. Self-expandable metallic stents (SEMSs) are known as an alternative treatment used to avoid emergency operation. We aimed to evaluate the significance of SEMS placement as a bridge to surgery and the surgical outcomes of the elective operation. A consecutive 20 patients with obstructive colon cancer undergoing SEMS placement between June 2014 and February 2016 were included. The technical outcomes of the SEMS placement, surgical procedures, and surgical outcomes were evaluated retrospectively. Among them, 2 patients were treated with a SEMS palliatively, and the others were treated with a SEMS as a bridge to surgery. All SEMS were placed successfully at the first attempt, and there was no SEMS-related complication. Before surgery, all patients could be diagnosed histologically, and they were evaluated systemically including proximal colon or distant metastasis. The median time to operation after SEMS placement was 14 days (range 9–20 days). Seven of the 18 patients underwent a laparoscopic colectomy without conversion to laparotomy. All patients with stage II or III colon cancer underwent curative surgery, and 2 patients with stage IV colon cancer underwent a one-stage resection of the primary colon cancer and simultaneous liver metastasis after the evaluation of hepatic functional reserve. There was no mortality or SEMS-related complication in the perioperative period. SEMS placement as a bridge to surgery for patients with obstructive colon cancer is safe and effective to provide an adequate amount of time for a preoperative systemic management and evaluation.

Intraoperative colonoscopy in patients with colorectal cancer: Review of recent developments

The use of intraoperative colonoscopy has increased alongside progress in the development of colonoscopy-associated devices and techniques, including the colonoscope itself. In the present review, we focus on four circumstances in which intraoperative colonoscopy is beneficial to colorectal surgery: (i) intraoperative determination of a tumor's location; (ii) observation of the proximal colon in cases of obstructive colorectal cancer; (iii) confirmation of the integrity of anastomosis; and (iv) novel surgical techniques that combine laparoscopic and endoscopic surgery. In light of the findings of our review, a combination of colonoscopy and surgery-especially laparoscopic surgery-is expected to facilitate the optimal handling of a variety of colorectal tumors, ranging from benign cases to advanced and obstructive cases.

Role of colonic stents in the management of colorectal cancers

Colorectal cancer is one of the commonly encountered cancers across the Western World. In United Kingdom, this constitutes third most common ranked cancer and second most common ranked cause of cancer related deaths. Its acute presentation as a malignant colonic obstruction imposes challenges in its management. Colonic stent has been used for many years to alleviate acute obstruction in such cases allowing optimisation of patient’s physiological status and adequate staging of cancer. In this review, current literature evidence regarding use of colonic stent in acute malignant colonic obstruction is critically appraised and recommendations on the use of colonic stent are advocated.

Long-term outcomes after stenting as a “bridge to surgery” for the management of acute obstruction secondary to colorectal cancer

Obstructive symptoms are present in 8% of cases at the time of initial diagnosis in cases of colorectal cancer. Emergency surgery has been classically considered the treatment of choice in these patients. However, in the majority of studies, emergency colorectal surgery is burdened with higher morbidity and mortality rates than elective surgery, and many patients require temporal colostomy which deteriorates their quality of life and becomes permanent in 10%-40% of cases. The aim of stenting by-pass to surgery is to transform emergency surgery into elective surgery in order to improve surgical results, obtain an accurate tumoral staging and detection of synchronous lesions, stabilization of comorbidities and performance of laparoscopic surgery. Immediate results were more favourable in patients who were stented concerning primary anastomosis, permanent stoma, wound infection and overall morbidity, having the higher surgical risk patients the greater benefit. However, some findings laid out the possible implication of stenting in long-term results of oncologic treatment. Perforation after stenting is related to tumoral recurrence. In studies with perforation rates above 8%, higher recurrences rates in young patients and lower disease free survival have been shown. On the other hand, after stenting the number of removed lymph nodes in the surgical specimen is larger, patients can receive adjuvant chemotherapy earlier and in a greater percentage and the number of patients who can be surgically treated with laparoscopic surgery is larger. Finally, there are no consistent studies able to demonstrate that one strategy is superior to the other in terms of oncologic benefits. At present, it would seem wise to assume a higher initial complication rate in young patients without relevant comorbidities and to accept the risk of local recurrence in old patients (> 70 years) or with high surgical risk (ASA III/IV).

Adenomatous neoplasia: postsurgical incidence after normal preoperative CT colonography findings in the colon proximal to an occlusive cancer

PURPOSE

To determine the postoperative incidence of adenomatous neoplasia in the colon proximal to an occlusive colorectal cancer where preoperative computed tomographic (CT) colonography findings were normal.

MATERIALS AND METHODS

Institutional review board approval, with a waiver of informed consent, was obtained. This observational study included patients with occlusive colorectal cancer who underwent preoperative CT colonography between April 2007 and March 2010 that revealed normal findings (ie, no lesions ≥ 6 mm) in the proximal colon and who underwent postoperative colonoscopy. The primary outcome was postoperative colonoscopic discovery of clinically relevant lesions (ie, nondiminutive [≥ 6 mm] adenomas, advanced adenomas, or cancers) in the proximal colon. The cumulative incidence of clinically relevant lesions in preoperatively normal proximal colon over the postsurgical follow-up time was analyzed by using the Kaplan-Meier method.

RESULTS

The final cohort included 204 patients (102 men and 102 women; mean age, 57.3 years ± 11.3 [standard deviation]). At a total of 435 postoperative colonoscopies performed over a median follow-up of 29 months (range, 1-74 months), clinically relevant lesions were detected in the proximal colon in 30 patients: Nonadvanced adenomas were detected in 23 patients, and advanced adenomas were detected in seven patients. The cumulative incidence of clinically relevant adenomatous lesions in the preoperatively normal proximal colon 12 and 18 months after preoperative CT colonography was 8.1% (95% confidence interval [CI]: 3.9%, 12.2%) and 9.6% (95% CI: 5%, 14%), respectively. Clinically relevant adenomatous lesions found in the proximal colon within 18 months of preoperative CT colonography were nonadvanced adenomas in 10 of 15 patients.

CONCLUSION

When the portion of the colon proximal to an occlusive cancer is devoid of nondiminutive lesions at preoperative CT colonography, colonoscopy of the proximal colon following cancer resection rarely finds clinically relevant lesions and is unlikely to reveal any lesions requiring immediate removal until routine 1-year postsurgical follow-up. Online supplemental material is available for this article .

Role of preoperative CT colonography in patients with colorectal cancer

In patients with colorectal cancer (CRC), accurate preoperative evaluation is essential for a correct therapeutic plan. Colonoscopy and intravenous contrast-enhanced computed tomography (CT) are currently recommended in the preoperative work-up for CRC. Preoperative colonoscopy has some limitations such as misdiagnosis of synchronous cancers in cases of incomplete exploration of the colon and inaccurate tumor localization. Intravenous contrast-enhanced CT successfully documents distant metastases although it sometimes enables unsatisfactory locoregional staging. Computed tomography colonography (CTC) is obtained after gas insufflation of the colon and offers a comprehensive preoperative evaluation in patients with CRC, including a definition of the segmental location of the tumor, presence of synchronous lesions or lack thereof, and fairly accurate locoregional staging. CTC has some limitations, including a lack of biopsy capability, suboptimal sensitivity for synchronous small polyps, and unsatisfactory nodal staging. Bearing in mind these limitations, CTC could be employed as a “one-stop-shop” examination for preoperative assessment in patients with CRC.

CT colonography in the diagnosis and management of colorectal cancer: Emphasis on pre- and post-surgical evaluation

This article addresses the use of computed tomographic colonography (CTC) for the diagnosis and management of colorectal cancer, focusing on presurgical evaluation of the colon proximal to an occlusive cancer and surveillance after cancer resection surgery. The key evidences accumulated in the literature and future work needed are summarized. CTC is a technically robust and the most practical method to evaluate the colon proximal to an occlusive cancer, which prevents colonoscopic examination past the occlusion, either before or after metallic stent placement. The high sensitivity of CTC for detecting cancers and advanced adenomas in the proximal colon can help prevent additional surgical procedures in patients showing negative results. However, the accuracy of CTC for distinguishing intramural cancers from adenomas is low, and the technique is limited in guiding management when a medium-sized lesion that do not show invasive features such as pericolic extension or nodal metastasis is found in the proximal colon. A maximal diameter ≥ 15 mm has been proposed as a criterion for surgical removal of proximal lesions. However, this needs to be verified in a larger cohort. In addition, the influence of presurgical CTC results on the current post-cancer resection colonic surveillance timeline remains to be determined. CTC can be readily added to the routine abdominopelvic CT in the form of contrast-enhanced CTC, which can serve as an effective stand-alone tool for post-cancer resection surveillance of both the colorectum and extracolonic organs. Although the accuracy of CTC has been demonstrated, its role in the current colonoscopy-based postoperative colonic surveillance protocols remains to be determined. Readers of CTC also need to be knowledgeable on the colonic lesions that are unique to the postoperative colon.

Status and literature review of self-expandable metallic stents for malignant colorectal obstruction

Use of colorectal stents has increased dramatically over the last decades. Colorectal stents offer an alternative way to relieve fatal intestinal obstruction and can take place of emergency surgery, which associated with significant morbidity and mortality and a high incidence of stoma creation, to elective resection. Although there remain a few concerns regarding the use of stents as a bridge to surgical resection, use of self-expandable metallic stents for palliation in patients with unresectable disease has come to be generally accepted. Advantages of colorectal stents include acute restoration of luminal patency and allowance of time for proper staging and surgical optimization, and the well-known disadvantages are procedure-related complications including perforation, migration, and stent failure. General indications, procedures, and clinical outcomes as well as recent evidences regarding the use of colorectal stents will be discussed in this review.

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.

Preoperative colonoscopy for detection of synchronous neoplasms after insertion of self-expandable metal stents in occlusive colorectal cancer: comparison of covered and uncovered stents

Background/Aims

In patients with occlusive colorectal cancers, a complete preoperative evaluation of the colon proximal to the obstruction is often impossible. We aimed to evaluate the feasibility of preoperative colonoscopy after stent placement and to determine whether the success rate of colonoscopy differs between covered and uncovered stents.

Methods

Seventy-three patients with malignant colorectal obstruction were enrolled prospectively. In patients with a resectable cancer, a preoperative colonoscopy was performed after insertion of a self-expandable metal stent (SEMS). The success rate of complete preoperative colonoscopy was compared between covered and uncovered stents.

Results

Forty-five of 73 patients who underwent stent placement had a resectable cancer (61.6%). A complete preoperative colonoscopy was possible in 40 of 45 patients (88.9%). The success rate of complete preoperative colonoscopy was significantly lower in the covered-stent group when the obstructing mass lesion was located in the sigmoid colon (p=0.024). Synchronous cancer was detected in one patient (2.2%). Stent migration was observed in four patients with a covered stent.

Conclusions

A preoperative complete colonoscopy after SEMS placement was feasible and safe in most patients with malignant colorectal obstruction. Uncovered stents seem to have more advantages than covered stents in preoperative colonoscopy proximal to the obstruction.

Virtual colonoscopy: Utility, impact and overview

Computed tomography (CT) colonoscopy is a well-established technique for evaluation of colorectal cancer. Significant advances have been made in the technique of CT colonoscopy since its inception. Excellent results can be achieved in detecting both colorectal cancer and significant sized polyps as long as a meticulous technique is adopted while performing CT colonoscopy. Furthermore, it is important to realize that there is a learning curve involved in interpreting these studies and adequate experience is essential to achieve high sensitivity and specificity with this technique. Indications, contraindications, technique and interpretation, including potential pitfalls in CT colonoscopy imaging, are reviewed in this article. Recent advances and the current role of CT colonoscopy in colorectal cancer screening are also discussed.

Evidence review and status update on computed tomography colonography

Computed tomographic (CT) colonography is being implemented increasingly in the USA and Europe, and in many centers it has become the radiological technique of choice for imaging the whole colorectum. Although high diagnostic accuracy has been demonstrated in both screening and symptomatic populations, controversy persists regarding implementation, who should interpret the examination, and its cost effectiveness, particularly in the context of primary colorectal cancer screening. Published research in recent years has demonstrated efficacy in a wide range of patient groups, striking technical improvements, and high levels of patient acceptability. New developments continue in the fields of computer aided detection, digital cleansing, and integration into positron emission tomography. The purpose of this review is to bring the reader up-to-date with the latest developments in CT colonography, in particular, those of the last year.

Colorectal stents: do we have enough evidence?

BACKGROUND

The use of colonic stents has significantly evolved over the last few years. Emergency surgery for colonic obstructions is usually associated with significant mortality, morbidity and often stoma formation. Colonic stents provide an alternative way to relieve colonic obstruction, and hence avoiding the risks associated with emergency surgery. This literature review aims to summarize the important current evidence regarding colorectal stenting and show whether further evaluation of the procedure is required.

RESULTS

The available large number of non-randomized studies suggests that Self-Expandable-Metal-Stents (SEMS) placement for acute colonic obstruction could be considered as safe and effective alternative to surgery in experienced hands either as a bridge to surgery or as a palliative measure. This evidence has led to SEMS being widely adopted. However, randomized evidence has begun to show the defects that are inherent in the low level evidence that has so far supported SEMS use and it may be that reports of randomized controlled trials may clarify the patient population where SEMS placement is appropriate.

CONCLUSION

While we are still waiting for the outcome of the multicentre randomized controlled trials in the UK and Europe, clinicians must be aware of the current evidence limitations and apply SEMS use pragmatically.

Expandable metal stents for malignant colorectal strictures

The surgical management of malignant colorectal obstruction is still controversial and has higher associated mortality and complication rates compared with elective surgery. Placement of self-expanding metallic stents (SEMS) has been proposed as an alternative therapeutic approach for colonic decompression of patients with acute malignant obstruction. SEMS placement may be used both as a bridge to surgery in patients who are good candidates for curative resection and for palliation of those patients presenting with advanced stage disease or with severe comorbid medical illnesses.

Computed tomographic colonography

This article provides basic information about computed tomographic colonography (CTC) and reviews the preparation, methods, and tools required for the procedure. The clinical uses for CTC (screening/diagnosis of colon cancer and colonic obstruction) are outlined, and its accuracy and validity are compared with other diagnostic methods. A summary of the benefits and risks of the test are presented and the current practicalities for implementation are addressed.

Update on the indications and use of colonic stents

Self-expandable metal stent (SEMS) placement is a minimally invasive option for achieving acute colonic decompression in obstructed colorectal cancer. Colorectal stenting offers nonoperative, immediate, and effective colon decompression and allows bowel preparation for an elective oncologic resection. Patients who benefit the most are high-risk surgical patients and candidates for laparoscopic resection with complete obstruction, because emergency surgery can be avoided in more than 90% of patients. Colonic stent placement also offers effective palliation of malignant colonic obstruction, although it carries risks of delayed complications. When performed by experienced endoscopists, the technical success rate is high with a low procedural complication rate. Despite concerns of tumor seeding following endoscopic colorectal stent placement, no difference exists in oncologic long-term survival between patients who undergo stent placement followed by elective resection and those undergoing emergency bowel resection. Colorectal stents have also been used in selected patients with benign colonic strictures. Uncovered metal stents should be avoided in these patients, and fully covered stents are associated with high risk of migration. Patients with benign colonic stricture with acute colonic obstruction who are at high risk for emergency surgery can gain temporary relief of obstruction after SEMS placement; the stent can be removed en bloc with the colon specimen at surgery. This article reviews the techniques and indications of SEMS placement for benign and malignant colorectal obstructions.