Endoscopically deployed self-expanding metal stents can be used to restore intestinal continuity in patients with obstructing colon tumors. First introduced as a palliative treatment for unresectable malignancies in the early 1990s, [31] the practice rapidly evolved into a bridge towards one stage curative resections. The purported benefits include transformation from an emergent to an elective operation with reduced morbidity, mortality, length of stay, cost, rate of stoma formation, and increased minimally invasive techniques and survival [32–34].

Multiple case reports and institutional series have demonstrated the safety and efficacy of self-expanding metal stents to treat obstructing colorectal tumors. The large majority of treated tumors are left sided or rectal tumors. These tend to obstruct more often than right sided tumors, which are more commonly treated with right colectomy. Rectal tumors can be stented, however stents placed into the distal rectum are at risk of causing pain, tenesmus, or prolapsing through the anus. Most endoscopists can achieve a very high degree of technical success, on the order of 90–95 % [35, 36]. Success is dependent upon tumor size and location, but also the skill and experience of the endoscopist. Some authors have suggested a learning curve of 20–30 procedures [37–39]. Common procedural complications include perforation, migration, and late occlusion due to tumor in growth or stool impaction. A recent review of over 4000 procedures documented a perforation rate of 7.4 % [35]. Covered stents are more resistant to tumor in growth and late obstruction, while uncovered stents carry a lower rate of migration.

Stenting has grown in popularity as it provides a less invasive treatment for obstruction. Biagi et al. [40] demonstrated that the time to initiation of adjuvant chemotherapy effects survival, and stents have at least the theoretical benefit of enabling a far more expeditious initiation of treatment. Two general strategies have developed from the early experience: stenting as definitive palliation, and stenting as a bridge to surgery [41]. The minimally invasive nature of stenting makes it an attractive option for either goal, but this must be balanced by the effectiveness, morbidity, mortality, cost, rate of stomas, etc. A large number of publications have addressed these issues. The largest numbers of these are single center experiences and retrospective reviews. There are few high quality prospective or comparative trials. For this reason, systematic reviews and meta-analyses are useful approaches to evaluation of the relative value of stenting versus surgery.

Review of this literature seems to indicate that although it may be possible that stent perforation can increase recurrence or metastatic disease, it is much clearer that stenting as a bridge to surgery significantly reduces perioperative complications. A reduction in complications, in turn, has been correlated with improved survival in a recent analysis of more than 12,000 patients [69]. Therefore, patients with a high risk of perioperative complications may be best suited for stenting as a bridge [70, 71]. To be efficacious and maintain a reasonable level of safety, institutional rates of successful stent placement should be 90 % or better, and the rates of stent-related perforation should be 5–7 % or lower.

It is unlikely that a large scale RCT comparing stenting as a bridge to surgery will be conducted due the requirement of a very large sample size, difficulty with technical standardizations, and need for long-term cancer follow up. It would also be very difficult to standardize the surgical arm of such a trial – segmental resection vs Hartmann’s procedure vs total colectomy, stoma, etc. Therefore, meta-analyses, as imperfect as they are, may be the best source of data and recommendations.

The American Society of Colon and Rectal Surgeons (ASCRS) 2013 Practice Parameters for the Management of Rectal Cancer [72] addresses the issue of stenting. The authors reiterate that stenting should not be considered in the setting of perforation, massive bleeding, or lack of technical expertise. Technical success may be achievable, but is at risk for failure due to migration, pain, and incontinence when placed in the rectum. The authors do conclude that a stent may function as a bridge to surgery, and facilitate a primary anastomosis, or as a component of palliative treatment in the setting of metastatic disease. Surgeons were cautioned about the limited duration of patency of stents in light of the improving survival of patients on modern palliative chemotherapy. The recommendation was graded as a strong recommendation in favor of stenting based on low quality evidence.

Currently, trials of stenting versus surgery are being conducted at Nanfang Hospital in southern China, and at the Chinese University of Hong Kong (www.​clinicaltrials.​gov). In addition, other trials in progress are comparing devices such as covered versus uncovered stents.

When a patient with an obstructing colorectal cancer presents, the first decision that must addressed is the goals of care. Some patients may prefer to seek hospice care with comfort measures only, especially in the setting of metastatic disease. If the patient elects to pursue treatment, then the next decision is how to acutely manage the obstruction. The primary options are stenting or surgery. Most right-sided colon lesions are treated with right colectomy. These patients should undergo a brief period of resuscitation and optimization, followed by right colectomy with either primary anastomosis, ileostomy and mucous fistula, or anastomosis with proximal loop ileostomy, depending on the condition of the patient and the colon.

For left-sided colon lesions, endoscopic stenting is an attractive option. If the endoscopist has experience with stenting and there are no compelling reasons to proceed immediately to the operating room, such as perforation, then stenting should be considered. If successful, a thorough metastatic workup and medical optimization can proceed. If the patient has incurable disease, the stent may serve as definitive palliation. Patency can be expected for many months and may be repeated if needed. Occasionally, resection may be performed subsequently if the metastatic disease is stabilized and the primary tumor is symptomatic. If the patient appears to have potentially curable disease, stenting is also a good initial approach. Stenting as a bridge to surgery does appear to reduce the need for a stoma and reduces the rate of postoperative complications. Although not all stents are technically successful and there is a 5–7 % rate of perforation, stenting has the distinct advantage of conversion of an emergency operation into an elective operation with the ability to stage and stabilize the patient. Patients and their families should clearly understand that stenting is not universally successful, that there are complications, and that, if unsuccessful, immediate surgery would be necessary, as would have been offered otherwise.