Preoperative Colonic Stents Versus Emergency Surgery for Acute Left-Sided Malignant Colonic Obstruction: A Meta-analysis

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1 J Gastrointest Surg (2014) 18: DOI /s ORIGINAL ARTICLE Preoperative Colonic Stents Versus Emergency Surgery for Acute Left-Sided Malignant Colonic Obstruction: A Meta-analysis Xuan Huang & Bin Lv & Shuo Zhang & Lina Meng Received: 22 June 2013 /Accepted: 26 August 2013 /Published online: 30 October 2013 # 2013 The Society for Surgery of the Alimentary Tract Abstract Purpose The purpose of this paper is to evaluate the efficacy and safety of colonic stenting as a bridge to surgery versus emergency surgery for acute left-sided. Methods Randomized clinical trials (RCT) that compared the efficacy or safety of preoperative colonic stents versus emergency surgery for acute left-sided were searched in medical databases, including PubMed, OVID, EMBASE, and the Cochrane Library. Statistical heterogeneity between trials was evaluated by Revman 5.1 and was considered to exist at I 2 >50 %. Results Seven RCTs were identified. There was a total of 382 patients, 195 who received a colonic stent and 187 who received emergency surgery. Compared with the emergency surgery group, the colonic stent group achieved significantly more favorable rates of permanent stoma, primary anastomosis, wound infection, and overall complications. There was no significant difference between the two groups in anastomotic leakage, mortality, or intra-abdominal infection. Inspection of funnel plots for all outcome measures did not reveal evidence of publication bias. Conclusions Self-expanding metal stents serve as a safe and effective bridge to subsequent surgery in patients with obstructing left-sided colon cancer. They can significantly improve one-stage surgery rates, and decrease the rates of permanent stoma and wound infection. Keywords Stents. Colorectal surgery. Intestinal obstruction. Meta-analysis. Randomized controlled trial X. Huang: B. Lv (*) : S. Zhang : L. Meng Department of Gastroenterology, The First Affiliated Hospital, Zhejiang Chinese Medical University, 54 Youdian Road, Shangcheng District, Hangzhou City , Zhejiang Province, China @163.com Colorectal cancer (CRC) is a common malignant condition with high mortality rates. 1 A recent review reported that 8 29 % of patients with colorectal cancer present with an emergency obstruction of the large bowel at the time of diagnosis. 2 4 The management of acute left-sided colorectal obstruction, caused mainly by carcinoma, remains controversial. 5,6 Emergency colorectal surgery for acute obstruction is associated with a mortality rate of % and a morbidity rate of %, 7 11 both significantly higher than after elective surgery. Self-expanding metallic stents (SEMS) have been suggested to facilitate bowel decompression and act as a bridge to surgery for those with resectable disease. 12 Furthermore, SEMS have been associated with decreased morbidity, mortality, stoma formation, and wound infections compared with emergency surgery. 13,14 Endoscopic colon stenting as a bridge to elective surgery has significant advantages in terms of short- and long-term outcomes. 15 However, some studies have reported that the overall complication rate and mortality is similar between SEMS as a bridge to surgery and emergency surgery. 16 There were some limitations in two recent metaanalyses. One by Zhang et al. 17 found that stent placement before elective surgery did not adversely affect mortality and long-term survival, but the meta-analysis included some

2 J Gastrointest Surg (2014) 18: Fig. 1 Flow chart of article screening and inclusion retrospective studies, which could affect the results. A systematic review by Tan 18 that only a few studies were included indicated there were no differences in primary anastomosis and permanent stoma. To objectively evaluate the therapeutic effects and safety of SEMS as a bridge to surgery in the treatment of acute malignant left-sided colonic obstruction, a meta-analysis was conducted of randomized controlled trials (RCTs) published in recent years. Data and Methods Inclusion and Exclusion Criteria Inclusion criteria were: (1) RCTs; (2) patients with acute malignant left-sided colonic obstruction; (3) study design that compared preoperative colonic stenting and emergency surgery; and (4) assessment of therapeutic effects, including one or more parameters such as permanent stoma, one-stage surgery, wound infection, anastomotic leakage, mortality, intra-abdominal infection, overall morbidity. Exclusion criteria were: (1) incomplete data; (2) duplicate studies; (3) use of a colonic stent in a control group; (4) no diagnostic criteria for acute malignant left-sided colonic obstruction; and (5) baseline data that were not similar to those in other papers. Literature Retrieval and Data Collection Databases searched included the Cochrane Library, PubMed, OVID Evidence-Based Medicine Database, EMBASE, a fulltext database of Chinese journals, the VIP database, and the Wanfang database. All studies published from January 1990 to February 2013 were considered. Search terms included English search terms such as stent*, surgery or operation or colectomy or enterostomy or colostomy, intestinal obstruction or large bowel obstruction or colonic obstruction, random* controlled trial, zhijia (Chinese for stents); shoushu (Chinese for surgery); sui ji dui zhao (Chinese for randomized control); and changgengzu (Chinese for intestinal obstruction). Original papers or review articles concerning children or pregnant women were excluded. The current year s papers(2013)were also retrieved from the Chinese Journal of Digestion, the Chinese Journal of Internal Medicine, the Chinese Journal of Gastroenterology, Gastroenterology and Gut by manual searches. We also retrieved papers from the United States Digestive Disease Week and from the references of the

3 586 J Gastrointest Surg (2014) 18: Table 1 Clinical data of included articles Colonic stenting as a bridge to surgery Emergency surgery Days after stent Total cases Author Year Quality grade BMI Type of surgery BMI Type of surgery M/F Age Pathological staging (I/II/III/IV) M/F Age Pathological staging (I/II/III/IV) Cheung et al B / /7/8/ Ileostomy 4, PA 16 12/ /7/13/3 24 Hartmann 11, PA 13 Cuietal B / /5/24/ / /4/13/ van Hooft et al A / PA 20 27/ PA 20, temporary stoma 25 Pirlet et al B / PA18, Hartmann 6 13/ PA 14 Alcantara et al B / /2/11/2 PA 14 7/ /5/6/2 PA 13 Ho et al B /7 68 0/7/10/3 High anterior resection 15 9/ /6/5/7 High anterior resection 10 Ghazal et al A 60 12/ /19/5/0 Left hemicolectomy 18, anterior resection 11 11/ /19/4/0 TACIR 30 not described in the references, age mean age or median age, BMI body mass index, TACIR total abdominal colectomy and ileorectal anastomosis, PA primary anastomosis selected papers. Two authors independently selected papers according to the same standards. Controversial papers were discussed by all authors and a consensus was reached. Quality Evaluation To decrease heterogeneity and increase the reliability of the results, we graded each RCT for quality and only included higher-quality RCTs. Study quality was evaluated according to the quality evaluation criteria recommended in the Cochrane Reviewers Handbook Briefly, the quality of a study was rated A, B, or C, based on its randomization method, concealment of the randomization scheme, blinding, loss to follow-up, and drop-outs, as: A, low bias, fully meeting the four quality criteria, with the least possibility of bias; B, moderate bias, partially meeting one or more of the quality criteria, with a moderate possibility of bias; and C, high bias, completely missing one or more quality criteria, with a high possibility of bias. Data Analysis Data analysis was performed with Revman 5.1 software (Cochrane Collaboration). A heterogeneity test was performed on dichotomous data including permanent stoma, one-stage surgery, wound infection, anastomotic leakage, mortality, intraabdominal infection, and overall morbidity with odds ratio (OR). All ORs were cited with 95 % confidence intervals (CI). Statistical assessment was then performed using a χ 2 test of homogeneity and evaluation of the inconsistency index (I 2 ) statistic. I 2 > 50 % was considered statistically significant. A fixed-effect model was used to estimate the overall effect if OR was homogenous; if OR was non-homogenous, a random-effect model was used. A P value <0.05 was considered significant. Publication Bias Funnel plots were drawn with OR values for permanent stoma, one-stage surgery, wound infection, anastomotic leakage, mortality, intra-abdominal infection, and overall morbidity as the x-axis and with standard error (log OR) as the y-axis. Publication bias was evaluated by observing whether the funnel plot was symmetrical. Results Literature Search and Included Studies Initially, 105 papers were retrieved. Through reading the titles and abstracts, 81 papers that did not conform to the entry criteria were excluded, and 24 further articles were excluded after a review of the full text. Finally, seven RCT papers were selected (Fig. 1) Of the seven papers, five were grade B

4 J Gastrointest Surg (2014) 18: Fig. 2 Forrest plot for permanent stoma of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided and two were grade A. Finally, our study included 382 patients: 195 who were given a colonic stent, and 187 controls who received emergency surgery. Pooled data showed a mean success rate of colonic stent placement of 76.9 % (range, %). Characteristics of age, sex, location of tumor, pathological staging, and BMI were comparative between the two groups in each RCT. Two papers used loop ileostomy for temporary diversion as a staged approach. Table 1 shows the basic characteristics of the included studies. Analysis of Efficacy Indicators Permanent Stoma Three RCTs reported permanent stoma. The heterogeneity test indicated χ 2 =3.12 and I 2 =36 %, demonstrating homogeneity. Therefore, the fixed-effects model was adopted, and the OR was 0.28 (95 % CI: , P = 0.002) (Fig. 2). Analysis of the pooled data revealed that preoperative colonic stenting achieved significantly lower rates of permanent stoma than emergency surgery. Primary Anastomosis Primary anastomosis was reported in seven RCTs. The heterogeneity test indicated χ 2 =3.57 and I 2 =0 %, demonstrating homogeneity. Therefore, the fixedeffects model was adopted, and the OR was 2.01 (95 % CI: , P =0.007) (Fig. 3). The meta-analysis showed that colonic stenting achieved significantly higher success rates of primary anastomosis than emergency surgery. Mortality Mortality was reported in four RCTs. The heterogeneity test indicated χ 2 =3.61 and I 2 =17 %, demonstrating homogeneity. In the fixed-effects model, the OR was 0.88 (95 % CI: , P =0.76) (Fig. 4). Analysis of the pooled data revealed that colonic stenting achieved significantly lower mortality rates than emergency surgery. Complications Seven RCTs reported complications, including anastomotic leak, wound infection, intra-abdominal infection, and overall morbidity. Wound infection was reported in five RCTs. The heterogeneity test indicated χ 2 =1.27 and I 2 =0 %, demonstrating homogeneity. In the fixed-effects model, the OR was 0.31 (95 % CI: , P =0.004) (Fig. 5). Overall complication rates were reported in six RCTs. The heterogeneity test indicated χ 2 =21.5 and I 2 =77 %, demonstrating heterogeneity. Therefore, the random-effects model was adopted, and the OR was 0.30 (95 % CI: , P =0.03) (Fig. 6). One trial detailed that a guidewire-related perforation occurred in two patients and a stent-related perforation occurred in four patients. Anastomotic leak was reported in seven RCTs. The heterogeneity test indicated χ 2 =8.23 and I 2 =27 %, demonstrating homogeneity. In the fixed-effects model, the OR was Fig. 3 Forrest plot for primary anastomosis of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided

5 588 J Gastrointest Surg (2014) 18: Fig. 4 Forrest plot for mortality of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided malignant colonic obstruction 0.74 (95 % CI: , P =0.47) (Fig. 7). Intra-abdominal infection was reported in three RCTs. The heterogeneity test indicated χ 2 =1.45 and I 2 =0 %, demonstrating homogeneity. The fixed-effects model found an OR of 0.62 (95 % CI: , P =0.57) (Fig. 8). Compared with emergency surgery, preoperative colonic stenting achieved significantly lower rates of wound infection and overall complications. There was no significant difference between the two groups regarding anastomotic leakage and intra-abdominal infection. Publication Bias In the preoperative colonic stenting and emergency surgery groups, all funnel plots of permanent stoma, one-stage surgery, wound infection, anastomotic leakage, mortality, intraabdominal infection, and overall morbidity were symmetrical with the lower part broader than the upper, suggesting no publication bias. Discussion Colorectal cancer is the most common cause of large bowel obstruction, with almost 90 % of these strictures located at or distal to the splenic flexure. Colonic obstruction represents a surgical emergency associated with a high degree of morbidity and mortality because of the generally poor condition of the patients (underlying disease, dehydration, and electrolyte imbalance). 25,26 Mortality and morbidity rates for emergency surgical decompression are % and 50 %, respectively, as opposed to a mortality rate of % when patients undergo elective surgery. 27,28 Conventional therapies for relieving malignant colorectal obstruction include surgical resection (potentially curative) or palliative colostomy. Multistage procedures may also be undertaken, with resection and stoma formation in one procedure, followed by restoration of continuity in a second procedure. 29 However, a significant proportion of patients receiving a staged procedure never undergo reversal of the colostomy. 30 Colonic stenting was introduced in the early 1990s as a tool to treat. Colonic stenting was demonstrated to be useful in acute as a permanent treatment in those patients who appeared to be incurable after diagnostic work-up. 31,32 A series of studies showed an overall rate for relief of obstruction of %, with complications such as perforation (4 %), stent migration (10 12 %) and re-obstruction (7 10 %), causing a cumulative mortality of 1 %. 13,33,34 In our meta-analysis, stent-related perforations were reported in some studies. van Hooft et al. reported 6 stent-related perforations in 47 patients in the SEMS group, 19 and Pirlet et al. reported two stent perforations and eight silent perforations in 30 patients randomized to colonic stenting as a bridge to surgery. 22 Avoidance of excessive manipulation of the guidewire and excessive air insufflation is important. Balloon pre-dilatation is best avoided, as it is significantly associated Fig. 5 Forrest plot for anastomotic leak of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided

6 J Gastrointest Surg (2014) 18: Fig. 6 Forrest plot for wound infection of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided malignant colonic obstruction with perforation. 33 The placement of a colonic stent is not always technically possible or clinically successful. Surgery is necessary for stent migration, perforation, or failure of stenting. As a result of issues relating to stent complications, including occlusion with fecal matter, migration, and even perforation, newer colonic stent designs have been introduced. These include a dedicated Wallflex colonic stent that has a larger diameter (25 mm) and longer lengths (6, 9, 12 cm). 35 Recently, experience accumulated with colonic endolumenal stenting for large bowel obstruction 36 (treating the obstruction and then allowing subsequent elective singlestage surgery) has led to consideration of SEMS as a potential bridge to surgery. A systematic review including 88 studies (15 of which were comparative) 37 and another smaller systematic review 38 have suggested that SEMS insertion is safe and effective, but the validity of these findings is limited by the small sample sizes. Currently, little high-level evidence is available. There are few RCTs about preoperative colonic stents for the treatment of acute malignant left-sided colonic obstruction, and we only obtained seven papers. Of these, two papers were grade A and five grade B. Stents for palliative reasons were only described in one trial and exclusion criteria that encompassed metastatic cancer were mentioned in another trial. An intention-to-treat analysis was performed in included studies. When compared with emergency surgery, the ORs of Fig. 7 Forrest plot for intra-abdominal infection of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided Fig. 8 Forrest plot for overall morbidity of colonic stenting as a bridge to surgery versus emergency surgery for management of acute left-sided

7 590 J Gastrointest Surg (2014) 18: colonic stents for permanent stoma, primary anastomosis, wound infection, and overall complications were 0.28 (95 % CI: , P =0.002), 2.01 (95 % CI: , P = 0.007), 0.31 (95 % CI: , P =0.004), and 0.30 (95 % CI: , P =0.03), respectively, indicating that preoperative colonic stents could significantly improve the success rate of primary anastomosis, and decrease the rate of permanent stoma, and complications. Thus, we consider that in this setting, an emergency stent was placed to relieve symptoms of colonic obstruction, allowing medical resuscitation, optimization of medical comorbidities, bowel preparation, and staging. 39,40 Elective surgery has improved the rates of primary anastomosis, and accordingly decreased the rates of permanent stoma and wound infection. However, we found that ORs for anastomotic leakage, mortality, and intra-abdominal infection indicated no significant difference between the colonic stenting group and the emergency surgery group. This may be related to the emergency nature of the surgery, the type of surgeon (gastrointestinal surgeon, general surgeon), or the time after colonic stenting. 35 In two RCTs, colonic stenting also led to reduced risk of bleeding compared with emergency surgery. However, the placement of a colonic stent is not always associated with shorter hospitalization and surgical time. The measured data described by medians did not undergo meta-analysis. All papers selected for this study were high-quality RCTs and had the same diagnostic criteria. To decrease publication bias, we collected papers widely through multiple approaches including computer searches, manual searches, and reference retrospection. Among duplicate papers, short papers were excluded from this study to control for repeat publication bias. In the seven papers, there was complete information including inclusion criteria, sex, age, pathogenetic condition, and medications, and the matched pairs were good between the treatment group and the control group. However, this metaanalysis still had some limitations. There was heterogeneity between papers because tumor location, pathological staging, study design, and follow-up were different. There was also heterogeneity in overall morbidity. This heterogeneity will affect the results to some extent. Conclusion Our meta-analysis showed that SEMS serve as a safe and effective bridge to subsequent surgery in patients with obstructing left-sided colon cancer. The procedure significantly improves one-stage surgery rates, and decreases the rates of permanent stoma and wound infection. 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