A) Palliation: endoscopic colonic stents (SEMS) vs. colostomy (C)
There are three RCTs comparing colostomy vs. SEMS for palliation of malignant colonic obstruction [
36‐
38].
Xinopulos et al in 2004 randomized 30 patients. In the SEMS group placement of the stent was achieved in 93.3% (14/15 pt); there was no mortality. In 57% (8/14) of patients in which the stent was successfully placed, colonic obstruction was permanently released (i.e. until death). Mean survival was 21,4 month in SEMS group and 20,9 months in C group. Mean hospital stay was quite high in both groups and significantly higher in group C: 28 days vs. 60 days. This study presented several limitations, and the small sample size might have limited the ability to discern differences between groups [
36]
Fiori et al in 2004 randomized 22 patients to either C or SEMS: mortality was 0% in both groups, morbidity was similar. SEMS group had shorter time to oral intake, restoration of bowel function, and hospital stay. This study was also limited by the small simple size and by the lack of follow up [
37]
The Dutch Stent-in I multicenter RCT was planned to randomized patients with incurable colorectal cancer to SEMS or surgery: the study was terminated prematurely after enrolling 21 patients because four stent-related delayed perforations resulting in three deaths among 10 patients in the SEMS group. There are no clear explanation for such a high perforation rate; the authors pointed out that limited safety data existed fort he stent used in their study (WallFlex, Boston Scientific Natick, MA) [
38]. Indeed, subsequent studies of Wallflex stent for colonic obstruction reported a perforation rate of about 5% [
39‐
42] which is in line with what commonly observed with other stents [
42].
The feasibility, safety, and efficacy of SEMS have been analyzed by retrospective studies. There are four systematic reviews analysing the outcome of SEMS for large bowel obstruction with the Sebastian study being the most complete and focused one [
43‐
46]. He retrieved 54 studies with a total of 1198 patients and the median rates were: technical success 94%, the clinical success 91%, the colonic perforation 3,76%, the stent migration 10%, the re-obstruction 10%, stent-related mortality 1% [
44]. These studies have shown that colonic stenting is a relatively safe technique with high success rates.
The influence of colonic stents on oncologic outcomes has been questioned but no exhaustive answer is available. Indeed, several studies suggested that primary tumour resection with palliative intent, would prolong survival in patients with stage IV colorectal cancer [
47,
48]. However the power of these retrospective studies is poor due to the study design, no uniform adjuvant therapies among groups, and the bias to compare unresectable stage IV cancer patients with resectable stage IV cancer patients.
On the other hand, several comparative, retrospective studies did not show any significant difference in term of overall survival after 3 and 5 years of follow up, between emergency surgery and stent placement [
49,
50].
Colonic stents have an attractive role in a multimodality approach to obstructive colon cancer; however close clinical observation is required: for example there is one literature report that colonic stent may increase the risk of colon perforation in patients who are candidates for bevacizumab: thus according to authors alternative treatments to SEMS in these patients should be considered [
51].
Recommendation: in facilities with capability for stent placement, SEMS should be preferred to colostomy for palliation of OLCC since stent placement is associated with similar mortality/morbidity rates and shorter hospital stay (Grade of recommendation 2B).
Advice: authors cautiously suggest to consider alternative treatments to stent in patients eligible for further bevacizumab-based therapy
B) Bridge to surgery: endoscopic colonic stents and planned surgery vs. emergency surgery
Cheung et al. recently published a RCT comparing endolaparoscopic approach (24 pts) vs. conventional open surgery (24 pts). In patients who were randomized to the endolaparoscopic group, an SEMS placement for colon decompression was attempted within 24-30 hours from admission and an elective laparoscopic-assisted colectomy was performed within two weeks following SEMS placement. Patients who were randomized to the open surgery group underwent emergency HP or TC with ICI on the same day of admission. Over a 3-years period, 50 patients were enrolled and 48 were available for the final analysis (24 in the open surgery group and 24 in the endolaparoscopic group). Overall, only 6 of11 patients undergo HP had subsequent reversal; PRA was conducted in 13 patients all but two without covering stoma; two patients experienced anastomotic leak (2 out of 11, 18,8%) requiring end colostomy and one of these had subsequent reversal; thus 1-stage operation was performed successfully in 38% and 75% avoided a permanent colostomy. Colon decompression by SEMS was achieved in 83% of patients while the 17% had HP At the time of planned surgery, 67% of patients in the endolaparoscopic group had successful 1-stage operations performed and the 4 remaining patients had diverting ileostomy (33%); finally in the endolaparoscopic group no one was given a permanent stoma. Furthermore, patients randomized to the endolaparoscopic group compared to emergency surgery had significantly greater successful 1-stage operation (16 vs.9; p = 0,04), less cumulative blood loss (50 ml vs. 200; p = 0,01), less wound infection (2 vs. 8; p = 0,04), reduced incidence of anastomotic leak (0 vs.2; p = 0,045), and greater lymph-node harvest (23 vs.11; p = 0,05).
Cheung and colleagues suggest that colon decompression provides time for resuscitation, adequate staging, bowel preparation and safer, minimally-invasive elective resection. Indeed, the rate of primary anastomosis is twice that following emergent surgery, and the stoma rate and the postoperative complications are significantly reduced [
52].
Observational studies comparing SEMS followed by planned surgery with emergency surgery (HP, or PRA). Martinez-Santos in a prospective non-randomised study comparing 43 patients in the SEMS group with 29 patients in emergency surgery group reports a 95% technical success rate of SEMS; however only 26 patient in the SEMS group had a further surgical operation: at the time of planned surgery for SEMS the comparison of median rate between SEMS vs. emergency surgery shows: primary anastomosis was 84,6% vs. 41,4% with p = 0,0025; morbidity was 40% vs.62% p = 0,054; ICU stay was 0,3 vs.2,9 days p = 0,015; reintervention was 0% vs. 17% p = 0,014; mortality was 9% vs. 24% however without reaching statistical significance [
53]. However the study is somewhat confusing because it include also a large population of palliative SEMS (14) and the two population in SEMS are sometime mixed and then compared to emergency surgery group. Similar results are reported also in less robust retrospective studies [
50,
54].
Tinley in 2007 performed a meta-analysis of non-randomised studies that compared SEMS and open surgery for malignant large bowel obstruction: SEMS was attempted in 244 out of 451 patients (54,1%) with a success rate of 92,6%; mortality occurred in 14 (5,7%) in SEMS and in 25 (12,1%; p = 0,03) in emergency surgery [
55]. This metaanalysis however was likely impaired by the heterogeneity of studies, since both patients stented for palliation or as a bridge to surgery were included. In this meta-analysis mortality rate for stenting (5.7%) was much higher than the 0.6% rate reported in a large systematic review [
45]
Little is known on oncologic outcomes of using SEMS as a bridge to elective surgery. A recent paper recommended that surgery should be scheduled shortly after stent insertion because the risk of tumour seeding from perforation and dislocation of stent [
56]. However selection bias of indication and timing of stenting could explain the high level of complications reported with SEMS and consequently the advice of authors regarding long-term survival [
57]. Finally there is no study available comparing survival in SEMS versus other surgical options.
The cost effectiveness of SEMS is an important parameter as stents are very expensive. It is thought that their cost is offset by the shorter hospital stay and the lower rate of colostomy formation. Two decision analysis studies from the US and Canada calculated the cost-effectiveness of two competing strategies - colonic stent versus emergency primary resection for OLCC [
58,
59] Both concluded that colonic stent followed by elective surgery is more effective and cost efficient than emergency surgery. A small retrospective study from the UK in 1998 showed that palliative stenting compared to surgical decompression allows saving a mean of £1769, whereas the stenting as a bridge to elective resection vs. emergency HP followed by elective reversal saved a mean of £685 [
60]. A RCT from Greece comparing SEMS and colostomy for palliation of patients with inoperable malignant partial colonic obstruction showed very small difference in the costs, with the stent group being 6.9% (132 euros) more expensive per patient [
36]. Another study from Switzerland reported SEMS to be 19.7% less costly than surgery [
61]. None of these studies incorporated the hidden costs of stoma bags used in the community. Although stents seem to be cost effective, results are difficult to compare because costs calculations vary in different health care systems, costs differ for palliation and bridge to surgery, and the cost of stents is likely to decrease over time.
Recommendation: SEMS should be used as a bridge to elective surgery in referral centre hospitals with specific expertise and in selected patients mainly as their use seems associated with lower mortality rate, shorter hospital stay, and a lower colostomy formation rate (Grade of recommendation 1B).