Should we reconsider the use of self-expandable metal stents as a bridge to surgery in malignant colorectal obstruction?

A major concern of self-expandable metal stent (SEMS) placement as a bridge to elective surgery for malignant colonic obstruction is the impact of stent placement on the oncological outcome of the patient with a potentially curable cancer. The short term postoperative outcomes of SEMS as a bridge to surgery have been studied in several trials. The most recent meta-analysis of seven randomized controlled trials showed that preoperative stent placement in patients with malignant left-sided colonic obstruction did not reduce the postoperative mortality, but did show less overall morbidity, a higher primary anastomosis rate, and a lower permanent stoma rate compared with emergency resection [1]. So far, it has been difficult to balance these short term benefits against the long term oncological outcomes of preoperative stent placement, because data are scarce. Given the oncological uncertainty, SEMS placement as a bridge to surgery is not recommended as standard treatment in the new European Society of Gastrointestinal Endoscopy (ESGE) guideline [2]. However, preoperative SEMS placement is recommended for consideration in patients over the age of 70 years and/or American Society of Anesthesiologists (ASA) score of ≥ 3, because in this subgroup the risk of short term mortality caused by emergency surgery may well outweigh the oncological risk of stent placement [2].

The study by Erichsen et al. [3] in this issue of Endoscopy provides unique population-based data from Denmark for the period 2005 – 2010. The authors present the 5-year overall survival and recurrence rates for patients with colorectal cancer (CRC) who underwent either preoperative SEMS placement (n = 581) or urgent resection (n = 3333). The baseline Dukes’ stage and co-morbidity status were similar between the groups. The results suggested an association between the use of SEMS as a bridge to surgery and an increased risk of CRC recurrence after 5 years: the 5-year recurrence risk after SEMS placement was 39 % compared with 30 % after urgent resection (adjusted incidence rate ratio 1.12, 95 % confidence interval [CI] 0.99 – 1.28). However, the increased risk of recurrence did not translate into a worse 5-year overall survival rate: 49 % compared with 40 %, respectively (adjusted mortality rate ratio 0.98, 95 %CI 0.90 – 1.07). Interestingly, analysis of the 30-day mortality showed a significantly lower mortality rate after SEMS placement (8.1 % vs. 13.7 %), which may argue in favor of stenting. Although the authors do not address the issue directly, they revive the question of how to balance the short term benefits of SEMS placement as a bridge to surgery against the increased risk of recurrence.

Recently, another meta-analysis was published on the long term outcomes of SEMS placement as a bridge to surgery [4]. Matsuda et al. reported a 5-year overall survival rate of 57.2 % in 297 patients who received a SEMS as a bridge to surgery and 67.1 % in 575 patients who were treated with emergency resection (risk ratio [RR] 1.05, 95 %CI 0.80 – 1.37). The 5-year disease-free survival rates were 48.4 % and 59.0 %, respectively (RR 1.05, 95 %CI 0.87 – 1.27). Recurrence occurred in 31.3 % of patients after preoperative stent placement and in 27.2 % after emergency resection (RR 1.13, 95 %CI 0.82 – 1.54). Although the absolute risk difference of the 5-year overall and disease-free survival was 10 % in favor of acute resection and the recurrence rate was 4 % higher after SEMS placement, no statistical significance was reached [4]. So this study also does not provide a clear answer to the question of how to balance the short term benefits with the possible long term negative oncological consequences.

Whether the increased recurrence rate in the study by Erichsen et al. may have been influenced by overt or silent perforation is unclear, as these data were not available. This is regrettable because it may have shed light on the assumed association between stent perforation and recurrence, as was recently suggested by the long term results of the Dutch Stent-In 2 trial [5]. These long term data revealed disease recurrence in five out of six patients with a stent-related perforation [5]. This means that a stent perforation may turn a local tumor into a metastasized disease. Although the large majority of patients will have an uneventful preoperative course after stent placement, the risk of perforation has been reported in up to 12.8 % in a randomized trial [6]. Therefore, there is a significant risk of stent perforation that may change the oncological perspective of the patient with a potentially curable obstructing tumor. Based on the fact that the pooled postoperative mortality of the randomized trials on SEMS placement as a bridge to surgery was similar to emergency resection, and that stent placement may increase the oncological risk of recurrence, SEMS as a bridge to surgery is not recommended as standard treatment for malignant colonic obstruction [2].

However, this balance does not apply to patients with an increased surgical risk. The randomized trials on SEMS placement as a bridge to surgery did not differentiate between patients at low and high risk of postoperative mortality, but included anyone with a malignant colonic obstruction. It is well known that age and physical status are independent risk factors for postoperative mortality after surgery for CRC [7]. In the emergency setting of malignant obstruction, the 30-day mortality rate after acute resection is more than 15 % in patients aged over 70 years, and can rise up to 25 % and even higher when significant co-morbidity (ASA ≥ 3) is present [2] [8]. In this subgroup of patients the short term risk of postoperative mortality may outweigh the oncological risk of stent placement, and therefore SEMS as a bridge to surgery should be considered according to the recommendations of the ESGE guideline [2].

In conclusion, the study by Erichsen et al. provides unique long term oncological data on SEMS placement as a bridge to surgery and suggests an increased risk of recurrence after preoperative SEMS placement. However, their results also showed a short term benefit in postoperative mortality after SEMS placement. So the question remains as how to balance the short term benefits of stent placement against the oncological risk. In the general population, the increased risk of recurrence outweighs the short term benefits of preoperative stent placement. Therefore, according to the ESGE guideline, SEMS placement as a bridge to surgery should not be recommended as standard treatment. However, in patients with an increased risk of postoperative mortality, preoperative stent placement may be beneficial compared with an emergency resection by reducing the postoperative mortality. Consequently, placement of a SEMS as a bridge to surgery should be considered in patients with an increased risk of postoperative mortality (age > 70 years and/or ASA ≥ 3).

• References

• 1 Huang X, Lv B, Zhang S et al. Preoperative colonic stents versus emergency surgery for acute left-sided malignant colonic obstruction: a meta-analysis. J Gastrointest Surg 2014; 18: 584-591
• 2 van Hooft JE, van Halsema EE, Vanbiervliet G et al. Self-expandable metal stents for obstructing colonic and extracolonic cancer: European Society of Gastrointestinal Endoscopy (ESGE) clinical guideline. Endoscopy 2014; 46: 990-1053
• 3 Erichsen R, Horváth-Puhó E, Jacobsen JB et al. Long-term mortality and recurrence after colorectal cancer surgery with preoperative stenting: a Danish nationwide cohort study. Endoscopy 2015; 47: 517-524
• 4 Matsuda A, Miyashita M, Matsumoto S et al. Comparison of long-term outcomes of colonic stent as “bridge to surgery” and emergency surgery for malignant large-bowel obstruction: a meta-analysis. Ann Surg Oncol 2015; 22: 497-504
• 5 Sloothaak DA, van den Berg MW, Dijkgraaf MG et al. Oncological outcome of malignant colonic obstruction in the Dutch Stent-In 2 trial. Br J Surg 2014; 101: 1751-1757
• 6 van Hooft JE, Bemelman WA, Oldenburg B et al. Colonic stenting versus emergency surgery for acute left-sided malignant colonic obstruction: a multicentre randomised trial. Lancet Oncol 2011; 12: 344-352
• 7 Morris EJ, Taylor EF, Thomas JD et al. Thirty-day postoperative mortality after colorectal cancer surgery in England. Gut 2011; 60: 806-813
• 8 Iversen LH, Bulow S, Christensen IJ et al. Postoperative medical complications are the main cause of early death after emergency surgery for colonic cancer. Br J Surg 2008; 95: 1012-1019