These results demonstrated that duodenal C-SEMS placement and fixation with an OTSC for mGOO was successful in all cases and that 86.7% of the patients achieved clinical success. In particular, 53.3% of patients with mGOO could have full diets. The additional time required for the procedure was 8.9 ± 4.1 minutes, which may be within the permissible range. Moreover, no adverse events were related to the fixation method. Poor performance status was associated with clinical success as estimated by the GOOSS score (P = 0.03). Stent migration occurred in one case (6.7%) with no other adverse events. No asymptomatic stent migration was observed on periodic abdominal X-ray imaging.
Stent migration is a major adverse event of duodenal C-SEMSs. Kim et al.6 reported that stent migration was significantly associated with chemotherapy after stent placement. Isayama et al.17 recommended the use of longer stents to prevent stent occlusion caused by tumor in- or overgrowth at the uncovered portion. According to this recommendation, in this pilot study, we used the longest C-SEMS (120 mm) available in our country. We were fortunate to experience no cases of tumor in- or overgrowth. Once a duodenal C-SEMS has migrated into the jejunum, clinicians hope it will exit via the rectum or remain in the body without causing obstruction symptoms. Otherwise, with obstruction symptoms, surgical removal is required, and this exhausts patients with advanced cancer. In this study, we experienced one case with stent migration. Fortunately, we were able to remove the migrated C-SEMS using an enteroscope without surgery 27. It is important to accommodate asymptomatic migration, which is not included in stent dysfunction. Although this event fortuitously may not cause symptoms related to gastrointestinal obstruction, it potentially results in intestinal obstruction.
Table 3 lists some published articles about endoscopic duodenal covered metal stenting for mGOO 6–11, 14–24. The literature review assessed more than 1000 cases of endoscopic duodenal C-SEMS stenting and found that chemotherapy was administered after C-SEMS placement in 41.2% (range 11.4–78.6%), and that stent migration occurred in 14.5% (range 6.0–32.3%) of cases. Not all of the clinical studies carried out periodic abdominal X-ray imaging or follow-up endoscopy, so the real rate of stent migration might be higher because asymptomatic stent migration could have been missed. Kim et al.6 performed a routine 8-week follow-up endoscopy and found that 63% of cases with a distally migrating C-SEMS occurred in patients without any obstructive symptoms. Their prospective study confirmed stent migration in almost one-third of patients during total follow-up. Another important issue is that the rate of patients receiving chemotherapy varies in published articles. The chemotherapy regimen continues to change and evolve, and some prospective studies including RCTs excluded mGOO patients with poor performance status 10, 17. Patients with poor performance status tend to avoid receiving chemotherapy, so the rate of patients with mGOO receiving chemotherapy might be lower in real-world practice. We did not exclude patients with poor performance status, so 26.7% of patients in our study cohort received chemotherapy after the procedure. We found that poor performance status was associated with clinical success, defined as relief of GOOSS score ≥ 2 within 1 week. Although the result could be due to underlying disease, symptoms related to mGOO were relieved in all cases (at least 1 GOOSS score improvement). Endoscopic duodenal C-SEMS placement with fixation might be beneficial even in patients with poor performance status.
Previously, because there were no designated duodenal C-SEMSs, clinicians applied esophageal C-SEMSs for relief of mGOO symptoms 16. Due to the bended anatomy of the duodenum, stent fracture and gastrointestinal perforation became a serious problem. Recently, SEMSs with low axial force 28 (i.e., those that follow the gastrointestinal tract) have been preferred and widely used. As shown in Figs. 1C and 2D, a SEMS with low axial force resulting from the devised knit pattern easily follows the gastrointestinal tract. Both ends of the uncovered portion were designed to stick to the tumor to prevent migration. Furthermore, the range of proximal flare was widened (Fig. 1A). Even with these ingenious improvements, previous studies using the C-SEMS (flared-ComVi stent) 10, 22 could not prevent stent migration with complete satisfaction. In comparison, although our pilot study included a limited number of cases, we observed favorable results (23.1% and 12.1% [flared-ComVi stent only] vs 6.7% [flared-ComVi stent with OTSC fixation]). In previous attempts to prevent stent migration, Choi et al.23 used a C-SEMS with large star-shaped flaps and Choe et al.24 used a 40-mm diameter funnel shape. Those stents could prevent distal migration (no cases in both studies), but proximal migration occurred in 11.1% and 16.7% of cases, respectively. Thus, stent migration is still a challenging problem, but our fixation method that anchors C-SEMSs to the gastrointestinal tract may contribute to approaching the ideal endoscopic SEMS placement.
Not enough is known about the role of anchoring of duodenal C-SEMSs in preventing migration. One previous study 25 reported the usefulness of endoscopic clips generally used for closing perforations or controlling bleeding to prevent C-SEMS migration. We previously practiced this technique, but still encountered cases of C-SEMS migration, and even without stent migration the clips were often out of place as assessed by routinely performed abdominal X-rays. Therefore, we evaluated the feasibility and safety of anchoring methods using experimental models 26. The OTSC and suturing system had a significantly higher gripping force compared with the clipping system (OTSC vs. clip: 13.2 vs. 1.0 Newtons [N], P < 0.001; suture vs. clip: 8.5 vs. 1.0 N, P < 0.001). Based on pathological findings in a porcine model, OTSC compressed the submucosal layer but not the muscle layer, and we concluded that the method may be safe even for preventive use. The results revealed that SEMS fixation with an OTSC and suturing method is feasible compared with the clipping method. Because an endoscopic suturing device is not available for daily clinical use in our country, we conducted duodenal C-SEMS fixation using OTSC in patients with mGOO. In this pilot study, we did not observe adverse events, such as gastrointestinal perforation, related to OTSC placement. We also confirmed that the position of C-SEMSs and OTSCs was unchanged until the last follow-up in 93.3% of cases. Further large-scale research using our fixation method will be required to establish higher quality evidence. The one problem with this fixation method is the additional cost (79,800 Japanese yen; approximately 770 US dollars) for an OTSC. Further studies should be planned considering medical costs.
This study had some limitations. First, it was a pilot study with a limited number of cases, and was conducted at a single institution. Further large-scale multicenter prospective research will be required to verify the superiority of our method over other conventional treatments and assess medical costs. Second, we selected an OTSC for fixation to anchor the C-SEMS; other methods such as an endoscopic suturing system should be evaluated. Currently, this system is not available in our country; we hope it will be accepted as a daily clinical procedure in the future.
In conclusion, an OTSC used for fixation of duodenal C-SEMSs was safe and feasible for preventing stent migration in patients with mGOO. The treatment may bring benefits even for patients with poor performance status. We believe our efforts will contribute to establishing an anti-migratory method for duodenal C-SEMSs.