Large-diameter plastic biliary stents for unresectable distal malignant biliary strictures: Rehashing the same or rekindling more interest?

Biliary stenting via endoscopic retrograde cholangiopancreatography (ERCP) is well established as the preferred method of biliary drainage for unresectable distal malignant biliary strictures [1]. However, cholangitis, stent occlusion, and recurrent biliary obstruction after stent placement has plagued the practice of ERCP for decades. Many different stent types are available, with broad categorization into two main groups: (a) plastic stents, and (b) self-expanding metal stents (SEMS) which can be fully covered (FCSEMS), partially covered (PCSEMS), or uncovered (UCSEMS). Multiple studies have assessed the various types and properties of stents for maximizing stent patency and improving patient outcomes for biliary drainage. For distal malignant biliary strictures in patients with a life expectancy greater than 4 – 6 months, SEMS have become the standard of care because of similar technical success, longer patency, and lower risk of recurrent obstruction compared to plastic stents, translating to a more cost-effective approach for this patient population [2] [3] [4]. However, plastic stents, being cheaper than SEMS, continue to be used in many parts of the world where cost of the stent is a major factor, especially when the patient’s life expectancy is less than 3 – 4 months. So, the question of whether a larger-caliber plastic stent (diameter more than standard 10-Fr plastic stents) would be better becomes very relevant. Kadakia & Starnes retrospectively assessed 10-Fr and 11.5-Fr plastic stents and concluded that 10-Fr stents have the same success and adverse event rate as 11.5-French stents in the management of biliary tract obstruction and offered no significant advantage [5]. Similar results were reported by Pereira-Lima and co-investigators in their retrospective study [6]. Our group (Wagh et al.) also published a multicenter randomized study where 234 patients with malignant biliary obstruction were randomly allocated to receive an 11.5-Fr plastic stent (n = 119) or a 10-Fr plastic stent (n = 115) [7]. Technical success was similar for the 10-Fr and 11.5-Fr stent groups (99.1 % vs. 97.4 %, respectively; P = 0.37) and there was no statistically significant difference in stent survival between 10-Fr and 11.5-Fr stents (median 149 vs. 258 days, P = 0.16). We concluded that the theoretical advantage of improved bile flow for the 11.5-Fr stent did not translate into longer patency, better clinical response, or longer patient survival than the 10-Fr stent. Overall, these larger-caliber plastic stents are not routinely used in clinical practice and have not been directly compared with SEMS.

“The saga of ‘bigger’ versus ‘better’ for biliary stents for unresectable distal malignant biliary obstruction continues, and Deprez and colleagues have infused new enthusiasm on this topic.”

Along these lines, in this issue of Endoscopy, Deprez and colleagues present their experience with a new 12-Fr plastic biliary stent for unresectable distal malignant biliary obstruction [8]. The authors are to be commended for renewing our interest in these larger-caliber stents by providing data from a well-executed study. In a prospective observational study, these investigators assessed 24 patients who underwent ERCP with placement of a new 12-Fr plastic biliary stent for unresectable distal malignant biliary obstruction. Of note, the new 12-Fr stent (Olympus Europe, Berchem, Belgium) is not currently commercially available (personal communication from the authors) and was used only for purposes of this study. They compared outcomes with this 12-Fr plastic biliary stent with historical matched controls consisting of patients who had 10-Fr plastic stents (n = 16) and SEMS (n = 32, including 16 fully covered and 16 uncovered). There was no difference in stent patency time between the stent groups, and recurrent biliary obstruction was significantly lower in the 12-Fr group compared with the 10-Fr group (50 % vs. 81.3 %, P = 0.04), and similar to that for FCSEMS (50 % vs 43.8 %, P = 0.698). The study is exciting and rekindles the age-old question – is bigger better?

However, after reviewing their manuscript, a few questions and limitations come to mind. The main limitation of this study is that it is not a randomized controlled study comparing the 12-Fr stent with standard 10-Fr plastic stents and with SEMS, especially when prior studies have not shown any significant additional benefit with larger-caliber plastic stents. The positive results from the study by Deprez et al. may be due to the specific three-layered design of the new 12-Fr stent (inner fluorine-coated layer, middle metal coil layer, and outer layer of a special resin) which may have contributed to better outcomes. Another point to consider is that comparisons with historical controls may not be accurate because of advances in cancer treatments such as newer chemoradiotherapy regimens which might have affected patient survival and outcomes with the 12-Fr stent in more recent times. One of the main reasons why larger-caliber plastic stents have not gained popularity is the technical difficulty in placing these bulkier stents and prior data suggesting no added benefit. The authors report that technical success was 100 % in placement of these newer stents, but they describe a specific technique for stent deployment without using the elevator on the duodenoscope. It would have been helpful to have also included an assessment of the degree of difficulty (possibly with a Likert scale) in placing these bigger cumbersome stents, and whether there was a learning curve effect, especially across tight strictures. Similarly, assessment of stent patency by visual inspection is often fraught with subjectivity especially since the evaluators were not blinded. Also, the irrigation test described in the ex vivo testing used data from 1960 which may not be optimal currently since physical stent characteristics have greatly changed over the last few decades.

Nevertheless, results from this study with the new 12-Fr stent are promising and may offer cost savings over SEMS. The saga of “bigger” versus “better” for biliary stents for unresectable distal malignant biliary obstruction continues, and Deprez and colleagues have infused new enthusiasm on this topic. We look forward to getting more experience with this new stent as it becomes more readily available across global markets, and hope that future randomized studies will help shed more light on choosing the best stent for relieving biliary obstruction.

Publication History

Article published online:
27 May 2020

• References

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