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Optimizing biliary stenting in patients with distal malignant biliary obstructionReferring to Chun JW et al. p. 563–568
“We should not moor a ship with one anchor, or our life with one hope”
Endoscopic biliary stenting plays a crucial part in the management of patients with malignant biliary strictures (MBSs), not only in a palliative setting where there is metastatic disease, but also in allowing neoadjuvant chemotherapy to be given before surgery . The use of self-expandable metal stents (SEMSs) is preferred to plastic stents, as SEMSs are associated with a longer patient survival, a lower risk of stent dysfunction/cholangitis, and fewer reinterventions . Fully covered SEMSs (FCSEMSs) have the advantage of being less prone to obstruction owing to tissue ingrowth, which allows easier stent removal; on the other hand, migration, into the duodenal lumen or even in an intrabiliary direction, can be of a major concern . Neoadjuvant chemotherapy seems to be an additional risk factor that favors migration, which relates to the reduction in tumoral tissue . Another debatable concern with the use of FCSEMSs is the incidence of cholecystitis, especially in patients presenting with tumor involvement of the cystic duct .
“… the advantage of an externally anchored plastic stent is the maintenance of biliary drainage by the plastic stent if it remains in the original position, even after migration of the FCSEMS.”
In the current issue of Endoscopy, Chun et al. demonstrate a novel technique to mitigate migration of FCSEMSs, with the aid of a 7-Fr pigtail plastic stent anchored externally . In this multicenter retrospective study including 185 patients with distal MBSs, mostly due to pancreatic cancer, 65 patients had an FCSEMS alone, and 120 had an FCSEMS with an external plastic stent. Stent patency was defined as the time between placement of the stent and stent revision owing to any stent dysfunction attributable to migration or occlusion, or other causes requiring reintervention The median stent patency was significantly longer in the group with an FCSEMS with an external plastic stent than in the FCSEMS only group (342 vs. 240 days; P = 0.04). Moreover, the rate of stent migration was significantly lower in the FCSEMS with an external plastic stent group than in the FCSEMS only group (10.8 % vs. 27.7 %; P = 0.01). The use of an external plastic stent was associated with stent patency in a multivariate analysis. Nevertheless, there were no significant differences regarding the need for reintervention for stent revision and the occurrence of adverse events (AEs). Specifically, the incidence of cholecystitis was 6.4 %, with no significant difference between the two groups.
The same authors have recently reported that anchoring with a 7-Fr double-pigtail stent inside an FCSEMS prevented stent migration and prolonged stent patency compared with an FCSEMS alone in a randomized controlled trial (RCT) . Although both techniques have similar antimigration efficacy, the advantage of an externally anchored plastic stent is the maintenance of biliary drainage by the plastic stent if it remains in the original position, even after migration of the FCSEMS. Indeed, in the current study, among the patients in the FCSEMS with an external plastic stent group whose FCSEMS migrated, the plastic stent remained in the original position for most patients, therefore ensuring ongoing biliary drainage.
Although the described technique seems to be an elegant and affordable way to prevent migration of FCSEMSs, the debate is still open regarding the choice between uncovered SEMSs (USEMSs), partially covered SEMSs (PCSEMSs), or FCSEMSs. A multicenter RCT of 119 patients with MBS due to pancreatic cancer receiving neoadjuvant chemotherapy that compared FCSEMSs and USEMSs showed an equal sustained biliary drainage (72.2 % vs. 72.9 %) . Tumor ingrowth was observed in 0 % vs. 16.7 % (P < 0.01) and stent migration in 6 % vs. 0 % (P = 0.03). Acute cholecystitis rates did not differ significantly between the two groups (9.3 % [4/43] for FCSEMSs vs. 4.8 % [2/42] for USEMSs; P = 0.08). Finally, predictors of failure to decompress a biliary obstruction were the use of shorter SEMSs (4-cm long compared with 6- and 8-cm long) and the presence of the gallbladder, but not the type of stent.
Another RCT, including 158 patients with MBS due to inoperable pancreatic cancer and therefore mostly receiving palliative chemotherapy, also compared FCSEMSs with USEMSs . FCSEMSs had a lower stent patency (240 vs. 541 days for USEMSs; P = 0.03) and were associated with more stent-related AEs as measured by stent dysfunction (overall AEs were 26.4 % for FCSEMSs vs. 13.2 % for USEMSs, although this was not statistically significant). FCSEMS dysfunction included migration and early occlusion, mainly due to sludge and overgrowth. On the other hand, USEMSs showed more ingrowth of tumor (13.2 % vs. 0 % in FCSEMSs; P = 0.001).
Finally, in a meta-analysis (11 RCTs, 1272 patients), which also included studies evaluating PCSEMSs, grouping these with the FCSEMSs (covered SEMS group), the primary outcomes of stent failure and patient mortality did not differ significantly between the covered and uncovered SEMS groups . Comparable to the aforementioned studies, stent migration and sludge formation were however much more common with covered SEMSs. The use of covered SEMSs was associated with a lower rate of tumor ingrowth, but a higher rate of tumor overgrowth compared with uncovered SEMSs. The rates of procedure-related AEs were similar in the two groups.
To summarize, there does not seem to be robust evidence supporting the superiority of a specific SEMS type, but it seems that the use of USEMSs could mitigate the risk of migration, and therefore stent dysfunction. Furthermore, the use of SEMSs, even USEMSs which cannot be extracted, does not seem to influence resectability and surgical outcomes during pancreaticoduodenectomy, therefore confirming their potential use in patients with borderline resectable pancreatic cancer undergoing neoadjuvant chemotherapy who are potential surgical candidates .
Nevertheless, a final note of caution should be underlined regarding the use of USEMSs for patients with undetermined biliary strictures. Up to 10 % of patients with presumed MBS will end up being diagnosed with a benign disease, so it is therefore crucial to avoid placing a USEMS in a patient where there is still doubt regarding the final diagnosis; indeed, USEMSs are very challenging to remove and can substantially impact the quality of life of these patients. In such cases, FCSEMSs are a safe alternative .
Article published online:
07 March 2023
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