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Keywords:

  • biliary stenting;
  • distal malignant biliary obstruction;
  • metallic stent;
  • plastic stent

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References

Endoscopic biliary drainage with biliary stent placement is the treatment of choice for palliation in patients with malignant biliary obstruction caused by unresectable neoplasms. Various biliary stent designs have become available, but lack of a clear consensus persists on the use of covered versus uncovered metal stents in malignant distal bile duct obstructions, and plastic versus metal stents. In 2012, the European Society of Gastrointestinal Endoscopy indicated guidelines for biliary stenting. Accordingly, the consensus meeting for biliary stenting was held at the Endoscopic Forum Japan 2012, and four selected statements related to stent placement for distal malignant biliary obstruction were discussed to produce a consensus. Two of fourstatements (related to the usefulness of self-expandable metallic stents, and reintervention after stenting) were agreed upon by almost all participants. Nevertheless, our opinions were divided on the other two statements (necessity of sphincterotomy for stenting, and covered metal stent versus uncovered metal stent). We herein report the results of the meeting, and present proposed new statements via discussion.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References

Malignant biliary obstruction can result from direct tumor infiltration, extrinsic compression, adjacent inflammation, desmoplastic reaction from tumors or, more commonly, a combination of these factors. Endoscopic biliary drainage with biliary stent placement is the treatment of choice for palliation in patients with malignant biliary obstruction caused by unresectable neoplasms. In particular, patients with unresectable malignant obstruction of the distal bile duct can be palliated by endoscopic biliary stenting in up to 95% of cases, with lower morbidity than for surgery. Perhaps biliary stenting provides a survival benefit.[1-4] Various biliary stent designs have become available, but a clear consensus remains elusive on the use of covered versus uncovered metal stents in malignant distal bile duct obstructions, and plastic versus metal stents. Additionally, it remains controversial whether or not sphincterotomy before stenting is necessary.

In 2012, the European Society of Gastrointestinal Endoscopy (ESGE) published guidelines for biliary stenting, entitled ‘Biliary stenting: Indications, choice of stents and results: European Society of Gastrointestinal Endoscopy (ESGE) clinical guideline’.[5] Although these guidelines represent the standard procedures of endoscopic biliary stenting with sufficient evidence, several issues remain a matter of debate. In August 2012, the Endoscopic Forum Japan (EFJ 2012) was held in Otaru, Hokkaido, Japan. There, we had a consensus meeting related to biliary stenting for unresectable malignant biliary strictures, which were prepared based on the ESGE guidelines (moderators were Akio Katanuma and Atsushi Irisawa, followed by a keynote lecture from Takao Itoi). In the present article, the authors present the results of our consensus meeting, and point to the controversial issues on biliary stenting in the ESGE guidelines.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References

Statements

We prepared seven statements based on the ESGE guidelines. Four statements are related to distal (lower and middle parts of bile duct) malignant biliary strictures (Statements LM1–LM4). Three statements are related to hilar strictures (Statements H1–H3). Each statement was sent to the 13 expert participants/discussants by email before the consensus meeting at EFJ 2012. Categorization of evidence and the voting schema were modified according to the Canadian Task Force on the Periodic Health Examination (Table 1). Choices of voting on statements were categorized as follows: a, accept completely; b, accept with some reservation; c, accept with major reservation; d, reject with reservation; and e, reject completely.

Table 1. Quality of evidence and voting on statements
Category and gradeDescription
  1. RCT, randomized controlled trial.

Quality of evidence 
1++High-quality meta-analyses, systematic reviews of RCT, or RCT with a very low risk of bias
1+Well-conducted meta-analyses, systematic reviews of RCT, or RCT with a low risk of bias
1−Meta-analyses, systematic reviews, or RCT with a high risk of bias
2++High-quality systematic reviews of case–control or cohort studies; high-quality case–control studies or cohort studies with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal
2+Well-conducted case–control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal
2−Case–control or cohort studies with a high risk of confounding, bias, or chance and a significant risk that the relationship is not causal
3Non-analytical studies, e.g. case reports, case series
4Expert opinion
Voting on statement 
aAccept completely
bAccept with some reservation
cAccept with major reservation
dReject with reservation
eReject completely

In the consensus meeting, moderators presented each statement before voting. We subsequently voted on each statement by a show of hands reflecting whether or not discussants agreed with the statement (the first vote). After the votes were counted, the result was announced. Subsequently, the pre-assigned discussants presented their views related to each statement, and all participants discussed several issues unreservedly. Finally, we voted again to produce a consensus after discussion. Similarly, votes were taken on the other six statements in succession.

Consensus among discussants was regarded as achieved when at least 80% of voting members gave a response of ‘accept completely’ or ‘accept with some reservation’. A statement was refused when at least 80% of voting members gave a response of ‘reject completely’ or ‘reject with some reservation’. If no consensus had been achieved after the final vote, the moderators sent altered statements to all participants/discussants by email after the meeting, and asked them again whether they would agree with the altered statement.

Membership of the consensus meeting

Voting members of the consensus group were selected using the following criteria:

  1. Demonstration of knowledge and expertise in biliary stenting through publication/research or participation in national or regional guidelines development.
  2. Geographical representation of the Asia region including Japan.

Representative countries were Japan, China, India, Korea, and Thailand.

The members of this consensus meeting were the following 13 individuals: Hirotoshi Ishiwatari (Sapporo Medical University), Kei Ito (Sendai Open Hospital), Takao Itoi (Tokyo Medical University), Hiroyuki Isayama (The University of Tokyo), Naoki Okano (Toho University), Ichiro Yasuda (Gifu University), Hiroki Kawashima (Nagoya University), Hironari Kato (Okayama University), Yoshinobu Okabe (Kurume University), Dong Wang (Changhai Hospital), Jong Ho Moon (Soon Chun Hyang University Bucheon Hospital), Sundeep Lakhtakia (Asian Institute of Gastroenterology), and Rungusun Rerknimitr (Chulalongkorn University Hospital).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References

We discussed and voted on four statements of biliary stenting for unresectable distal malignant biliary obstruction (Table 2).

Table 2. Results of voting on statements for distal malignant biliary stricture
 StatementFirst voteFinal voteConsensus
LM1Biliary sphincterotomy is not necessary for inserting a single plastic stent or a self-expandable metallic stent (SEMS).

a: 0%

b: 15%

c: 62%

d: 23%

e: 0%

a: 0%

b: 23%

c: 62%

d: 15%

e: 0%

Disagree
Altered LM1In cases of pancreatic cancer, biliary sphincterotomy is not necessary for inserting a single plastic stent or a self-expandable metallic stent (SEMS). 

a: 17%

b: 66%

c: 17%

d: 0%

e: 0%

Agree
LM2SEMS present a lower risk of recurring biliary obstruction than do single plastic stents, without difference in patients.

a: 77%

b: 23%

c: 0%

d: 0%

e: 0%

a: 69%

b: 31%

c: 0%

d: 0%

e: 0%

Agree
LM3Among SEMS models of 10-mm diameter, no difference has been clearly demonstrated, including that between covered and uncovered models.

a: 0%

b: 54%

c: 23%

d: 23%

e: 0%

a: 0%

b: 46%

c: 8%

d: 46%

e: 0%

Disagree
Altered LM3In cases of pancreatic cancer, among SEMS models of 10-mm diameter, no difference has been clearly demonstrated, including between covered and uncovered models. 

a: 0%

b: 84%

c: 8%

d: 8%

e: 0%

Agree
LM4For occluded SEMS, mechanical SEMS cleansing is poorly effective for restoring biliary patency; inserting a second SEMS within the occluded SEMS yields a longer biliary patency than inserting a plastic stent.

a: 0%

b: 85%

c: 15%

d: 0%

e: 0%

a: 0%

b: 85%

c: 15%

d: 0%

e: 0%

Agree

Statement LM1

Biliary sphincterotomy is not necessary for inserting a single plastic stent or a self-expandable metallic stent (SEMS). (Evidence level 1+)

Level of agreement

First vote: a, 0%; b, 15%; c, 62%; d, 23%; e, 0%

Final vote: a, 0%; b, 23%; c, 62%; d, 15%; e, 0%

For this statement, only 23% consensus was achieved at the final vote. Many discussants reported ‘Accept with major reservation’. Discussion points after the first vote were the following:

  1. Pancreatic cancer is the most common cause of distal malignant biliary obstruction. These patients have a low risk of pancreatitis because of occlusion of the pancreatic duct orifice. However, malignant diseases causing distal biliary obstruction include not only pancreatic cancer, but also biliary carcinoma and metastatic diseases. In these patients, pancreatic ducts have no involvement of the neoplasm (the main pancreatic duct is alive).
  2. Although the sizes of plastic stents and SEMS differ, these two types of stents are written down in the same way in this statement. In addition, several kinds of SEMS exist: bare, partially covered, and fully covered. These are not reflected in this statement.
  3. There is no consideration of the ampullary size in individuals.

In fact, an important question remains: Does deploying SEMS without sphincterotomy cause pancreatitis or not? Until now, no reliable randomized trial has been reported. However, some reports of the literature describe the indication of sphincterotomy before deploying SEMS. Artifon et al.[6] reported that routine sphincterotomy before SEMS deployment for distal common bile duct obstruction from pancreatic cancer is unnecessary and associated with higher rates of complications including stent migration, bleeding, and perforation. Moreover, Shimizu et al.[7] reported non-pancreatic cancer cases as predictive factors for pancreatitis after stenting of covered SEMS. In addition, Kawakubo et al.[8] showed SEMS with high axial force and reported that an etiology of malignant biliary obstruction other than pancreatic cancer is strongly associated with a high incidence of pancreatitis. Therefore, in pancreatic cancer with main pancreatic duct obstruction, it is considered that no need exists to carry out sphincterotomy for insertion of either a plastic stent or a SEMS. However, in bile duct cancer or lymph node metastasis of another organ cancer, randomized trial data have not been reported, and pancreatitis after insertion of a SEMS without sphincterotomy occasionally happened. Therefore, it is difficult to reach a consensus in the presented statement: There is no need to carry out sphincterotomy in these patients. In conclusion of this section – whether or not sphincterotomy is done – a majority opinion is necessary. However, more case information is necessary, such as pancreatic duct situation, stent diameter, and ampulla size. Based on the discussion, the statement was changed to the following:

Altered statement LM1

In cases of pancreatic cancer, biliary sphincterotomy is not necessary for inserting a single plastic stent or a self-expandable metallic stent (SEMS).

Level of agreement for altered statement

Vote: a, 17%; b, 66%; c, 17%; d, 0%; e, 0%

Statement LM2

SEMS present a lower risk of recurring biliary obstruction than do single plastic stents, without difference in patients. (Evidence level 1+)

Level of agreement

First vote: a, 77%; b, 23%; c, 0%; d, 0%; e, 0%

Final vote: a, 69%; b, 31%; c, 0%; d, 0%; e, 0%

For this statement, 100% consensus was achieved at the first and at the final vote. All voting members recommended the usefulness of SEMS for distal biliary obstruction. Both plastic stents and SEMS are useful for the palliation of malignant distal bile duct obstructions.[9] Plastic stents are less expensive than SEMS, and can be removed and replaced easily if they become occluded. However, plastic stents have limited stent patency because they have a narrow lumen (7–10 Fr), and easily become occluded with biliary sludge and/or bacterial biofilm comprising protein etc.[10] SEMS were developed to overcome the diameter limitation of plastic stents because they deliver stents with diameters as large as 8–10 mm (up to 30 Fr). This larger diameter facilitates biliary flow and improves patency rates.[11] In comparison studies of plastic stents and SEMS, the patency rates of SEMS were superior to those of plastic stents for distal biliary obstruction, with 10–12 months versus 3–4 months.[12, 13] In patients with unresectable malignant biliary obstruction, the mean survival period is less than 1 year. Therefore, SEMS are intended to yield palliation of obstructive symptoms throughout the remaining lifespan of these patients.[14] Recently, however, a modified double-layer stent with two holes (18 gauge) on the proximal side of the tip (DLS; Olympus Medical Systems, Tokyo, Japan) has been developed. It was shown to be superior to a regular plastic stent and similar to covered SEMS with respect to patency.[15] In addition, some discussants indicated that plastic stent placement inside the bile duct (obstruction at middle part of bile duct) was effective. At present, this opinion is not supported by clear evidence. We considered that it should be examined in future studies. Possibly, the role of the plastic stent might be reviewed in years to come.

Statement LM3

Among SEMS models of 10-mm diameter, no difference has been clearly demonstrated, including that between covered and uncovered models. (Evidence level 1+)

Level of agreement

First vote: a, 0%; b, 54%; c, 23%; d, 23%; e, 0%

Final vote: a, 0%; b, 46%; c, 8%; d, 46%; e, 0%

In this statement, we reached no consensus during discussion. The opinions of discussants were divided into two categories of whether or not covered SEMS are superior. Isayama et al.[16] reported that covered SEMS prevented tumor ingrowth and that they were significantly superior to uncovered SEMS for the treatment of patients with distal malignant biliary obstruction. Subsequent to that report, reports of several randomized trials have been published.[17-20] However, they remain at odds. Although covered SEMS prevent tumor ingrowth, overgrowth remains a problem. In addition, potential problems of covered SEMS include bile encrustation, stent migration, and occlusion of the cystic duct and pancreatic duct. As described above, there is a high incidence of acute pancreatitis in using covered SEMS. Recently, a meta-analysis was published describing that the use of covered SEMS compared with uncovered SEMS in patients with distal malignant biliary obstruction was of unclear benefit because covered SEMS have a higher rate of migration and do not appear to have longer patency.[21]

In Japan,[16, 20] a significant difference in patency has been reported between covered and uncovered stents. However, in European countries and in the USA, the importance of covered SEMS is not widely accepted. From our discussion, it is considered that one reason is the type of stent and the placement method: in many European and American studies, a covered SEMS is placed below the cystic duct to avoid cholecystitis after stenting. Thereby, these authors were unable to cover the stricture position sufficiently. Therefore, in many cases, tumor ingrowth at the uncovered position and overgrowth might have occurred. In addition, a shorter metallic stent has insufficient compatibility in the bile duct, which causes the high rate of migration. Based on that discussion, the statement was changed as follows:

Altered statement LM3

In cases of pancreatic cancer, among SEMS models of 10-mm diameter, no difference has been clearly demonstrated, including between covered and uncovered models.

Level of agreement for altered statement

Vote: a, 0%; b, 84%; c, 8%; d, 8%; e, 0%

Statement LM4

For occluded SEMS, mechanical SEMS cleansing is poorly effective for restoring biliary patency; inserting a second SEMS within the occluded SEMS yields a longer biliary patency than inserting a plastic stent. (Evidence level 2–)

Level of agreement

First vote: a, 0%; b, 85%; c, 15%; d, 0%; e, 0%

Final vote: a, 0%; b, 85%; c, 15%; d, 0%; e, 0%

For this statement, 85% consensus was achieved at the first and at the final vote. Almost all voting members recommended the usefulness of inserting a second SEMS within the occluded SEMS. However, this statement includes covered and uncovered SEMS. Consequently, we had several opinions related to this issue as follows:

  1. In patients initially using covered SEMS, new covered SEMS should be deployed after removal of old covered SEMS.
  2. If the patient's lifespan is shorter than 3–4 months, the plastic stent is superior in terms of its cost and convenience. However, data do not sufficiently support the usefulness of reintervention in cases using covered SEMS, although they have the potential for removability.[22] Randomized trials are necessary to verify this opinion further.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References

A consensus meeting was held on the subject of unresectable malignant biliary strictures at EFJ 2012. Among the four basic statements related to biliary stenting for unresectable distal malignant biliary obstruction, we found consensus without altering statements for only two (50%) original statements. To devise near-perfect consensual statements, further studies are necessary in these areas.

Conflict of Interests

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References

Authors declare no conflict of interests for this article.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusion
  7. Conflict of Interests
  8. References
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