Role of endoscopic ultrasound-guided biliary drainage for palliation of malignant biliary obstruction

Abstract

Endoscopic ultrasound-guided biliary drainage (EUS-BD) directs bile flow into the digestive tract and has been mostly used in patients with malignant biliary obstruction (MBO) where endoscopic retrograde cholangiopancreatography-guided biliary drainage was unsuccessful or was not feasible. Lumen apposing metal stents (LAMS) are deployed during EUS-BD, with the newer electrocautery-enhanced LAMS reducing procedure time and complication rates due to the inbuilt cautery at the catheter tip. EUS-BD with electrocautery-enhanced LAMS has high technical and clinical success rates for palliation of MBO, with bleeding, cholangitis, and stent occlusion being the most common adverse events. Recent studies have even suggested comparable efficacy between EUS-BD and endoscopic retrograde cholangiopancreatography as the primary approach for distal MBO. In this editorial, we commented on the article by Peng et al published in the recent issue of the World Journal of Gastrointestinal Surgery in 2024.

Key Words: Endoscopic ultrasound; Endoscopic ultrasound guided biliary drainage; Cancer; Pancreas; Bile duct; Endoscopy

Core Tip: Among the various interventions available for biliary drainage in distal malignant biliary obstruction, guidelines recommend endoscopic retrograde cholangiopancreatography for primary drainage, with endoscopic ultrasound-guided biliary drainage being an alternative approach in poor surgical candidates at high volume expert centers.

INTRODUCTION

Malignant biliary obstruction (MBO) is most commonly caused by pancreatic ductal adenocarcinoma and cholangiocarcinoma, needing palliative decompression in poor surgical candidates[1]. Endoscopic retrograde cholangiopancreatography (ERCP) with placement of a self-expanding metal stent is the first-line therapeutic modality for distal MBO[2]. The success rate for ERCP-guided biliary drainage ranges from 90%-95%, with 50.0%-76.7% of stents remaining patent at 1 year[3,4]. Failure with ERCP may be seen in cases of tumor infiltration/obstruction, surgically altered anatomy, prior duodenal stenting or stenosis, and periampullary diverticulum[4]. Previously, percutaneous transhepatic biliary drainage (PTBD) was performed in patients with unsuccessful ERCP, owing to its easy availability and good success rates[5]. However, PTBD causes significant morbidity and adversely affects patients’ quality of life.

Endoscopic ultrasound-guided biliary drainage (EUS-BD) enables bile flow into the digestive tract, preventing manipulation of the papilla and decreasing the risk of post-procedural pancreatitis[6]. In patients with failed ERCP, EUS-BD is associated with a higher clinical success rate and a lower adverse event rate as compared to PTBD[7]. There are different stents available for use during EUS-BD: (1) “Tubular” stents carry risk of migration; (2) “Cold” lumen apposing metal stents (LAMS) involve multiple steps for placement due to lack of inbuilt cautery, thereby increasing risk of complications (i.e. loss of the wire and/or scope position, biliary leak)[8-10]; and (3) The electrocautery-enhanced (ECE) “hot” LAMSs have an integrated cautery at the catheter tip that allows placement of the stent directly without needing multiple steps[10]. EUS-BD with ECE-LAMS has shown excellent clinical outcomes in patients with MBO, with recent evidence even reporting EUS-BD to have similar technical/clinical success rates and lower procedure-related pancreatitis and stent dysfunction when compared to ERCP for first-line biliary drainage[11]. In this editorial, we commented on the article by Peng et al[12] published in the recent issue of the World Journal of Gastrointestinal Surgery 2024.

KEY FINDINGS

Peng et al[12] conducted an updated meta-analysis of EUS-BD with ECE-LAMS for palliation of MBO. A total of 14 single and multicenter studies, all published after 2018, with 620 patients (51.5% males) were included. Pancreatic cancer was the most common etiology of biliary obstruction. Others included cholangiocarcinoma, metastatic cancer, and ampullary cancer. The stent diameters used were: 6 mm (41.9%); 8 mm (39.3%); 10 mm (18.3%); and 15 mm (0.5%). The pooled outcomes with EUS-BD were: Technical success (from 14 studies) 96.7% [95% confidence interval (95%CI): 93.5%-98.9%]; clinical success (from 13 studies) 91.0% (95%CI: 86.0%-95.1%); adverse events (from 13 studies) 17.5% (95%CI: 12.2%-23.4%); and reintervention rate (from 13 studies) 7.3% (95%CI: 3.9%-11.5%). The results were found to be consistent in the subgroups based on region of origin, size and quality of study, year of publication (prior to or after 2021), and study scale (single center or multicenter). The most common adverse events were bleeding, cholangitis, and stent occlusion. The authors recognized several important limitations to their analysis, including lack of uniformity in defining clinical success, moderate heterogeneity in their outcomes, and inclusion of mostly retrospective reports from expert tertiary centers that could have resulted in selection bias.

The findings of this study are in line with the previously published literature on this topic[13,14]. In a recent meta-analysis of EUS-BD for all indications (155 studies, 7887 patients), the pooled outcomes found were: Clinical success 95%; adverse events 13.7%; bile leak 2.2%; cholangitis 1.0%; major adverse events 0.6%; procedure-related mortality 0.1%; delayed migration 1.7%; stent occlusion 11.0%; and reintervention 16.2%[15]. Furthermore, it is interesting to note that the specific technique of EUS-BD did not appear to alter the outcomes, i.e. EUS-guided hepaticogastrostomy (EUS-HGS) and EUS-guided choledochoduodenostomy (EUS-CDS) were shown to be similar in terms of technical/clinical success rates and adverse events in another recent meta-analysis[16]. In MBO patients where even EUS-BD fails, gallbladder drainage via EUS (EUS-GBD) can be performed with a reported success rate of 85%, adverse events of 13%, and stent dysfunction of 9%[17]. The increasing use of ECE-LAMS for a variety of clinical indications including drainage of intra-abdominal fluids, relieving obstruction of the gastrointestinal tract, gallbladder drainage, and drainage of pancreatic fluid collection and wall-off necrosis seems to be improving the success rates with a decreased rate of adverse events as compared to LAMS without electrocautery[18].

CURRENT GUIDELINES

The 2017 guidelines by the European Society of Gastrointestinal Endoscopy recommended ERCP over surgery or PTBD for decompression of malignant extrahepatic biliary obstruction[19]. Due to limited evidence at the time, EUS-BD was advised in cases where standard ERCP techniques had failed. The updated 2022 European Society of Gastrointestinal Endoscopy guidelines, however, recommended the following: (1) EUS-BD over PTBD after failed ERCP in distal MBO when local expertise is available; (2) ERCP for primary drainage of distal MBO, with EUS-BD being an alternative approach in poor surgical candidates at high volume expert centers; and (3) EUS-CDS over EUS-HGS in distal biliary obstruction due to a lower rate of adverse events[20].

Along similar lines, the 2023 American College of Gastroenterology guideline recommended EUS-BD over PTBD for biliary strictures in patients with unsuccessful or impossible ERCP, with an expert endoscopist performing the interventional EUS procedures[21]. Due to the procedural difficulty and higher risk of complications associated with conventional/”cold” LAMS (without inbuilt cautery), more and more gastroenterologists worldwide have been preferring ECE-LAMS[18,22]. Furthermore, as clinical experience increases in the use of ECE-LAMS during EUS, a proportional reduction in LAMS-related adverse events was observed[23].

CLINICAL IMPLICATIONS

The position of EUS-BD with ECE-LAMS for MBO patients is climbing up the decision tree in the guidelines with accumulating positive evidence in its favor. While Peng et al[12] included studies of EUS-BD with ECE-LAMS in patients with impossible/failed ERCP, upcoming evidence for EUS-BD is challenging ERCP as the primary approach in distal MBO. One of the initial randomized controlled trials (RCTs) comparing EUS-BD with ERCP for distal MBO (pancreatic cancer) was by Bang et al[24]. Both approaches were found to be similar in regard to adverse events (21.2% vs 14.7%, P = 0.49), technical/treatment success, and reinterventions. With a slightly larger study sample size, the RCT by Paik et al[25] showed possible superiority of EUS-BD compared to ERCP in terms of a lower rate of adverse events (6.3% vs 19.7%, P = 0.03) and preserved quality of life. Difficult biliary cannulation due to the tumor in ERCP along with subsequent tumor in-growth were likely the main reasons for the differences observed in this trial.

A recent RCT by Teoh et al[3] studied EUS-CDS with LAMS vs ERCP with covered metallic stents in patients with unresectable distal MBO. The former was associated with higher technical success (96.2% vs 76.3%, P < 0.001) and shorter procedural time (median 10 min vs 25 min, P < 0.001) with 1-year stent patency rates (91.1% vs 88.1%, P = 0.520), clinical success (93.7% vs 90.8%, P = 0.559), 30-d adverse events (P = 1.000), and 30-d mortality (P = 0.530) being similar in the two groups.

Another recent RCT by Chen et al[26] reported EUS-CDS to have shorter procedural time as compared with ERCP for distal MBO (mean 14.0 min vs 23.1 min, P < 0.01) with comparable rates of technical success (90.4% vs 83.1%), stent dysfunction (9.6% vs 9.9%, P = 0.96), adverse events, subsequent pancreaticoduodenectomy, oncologic outcomes, and quality of life.

Combining all the evidence from RCTs available to date, Gopakumar et al[11] performed a meta-analysis comparing EUS-BD vs ERCP for first-line drainage in distal MBO. They found similar technical success [risk ratio (RR): 1.05, P = 0.246] and clinical success (RR: 0.99, P = 0.850) along with a lower rate of procedure-related pancreatitis (0% vs 7.2%), stent dysfunction (RR: 0.48, P = 0.008), and mean procedure time (13.43 min vs 21.06 min) in the EUS-BD group.

There are multiple routes for EUS-BD, with EUS-CDS being the most commonly used. As noted above, newer meta-analyses showed similar adverse event rates in EUS-CDS and EUS-HGS, which likely warrants an update in the guidelines[16]. Among the LAMS, only the AXIOS stent (Boston Scientific, Marlborough, MA, United States) is currently available in the United States[27]. Other types such as the Niti-S SPAXUS stent (Taewoong Medical, Gyeonggi-do, South Korea) have longer length, larger flanges, and adjustable inter-flange distance prompting easier use by the gastroenterologists, with a possible further decrease in complication rates[28]. These stents are mainly used in Asian countries based on their availability. Most of the clinical studies used the HOT-AXIOS or HOT-SPAXUS stents for EUS-BD[29].

It is worthwhile to mention a few other recent studies that may impact procedure choice in the future for biliary drainage. In a multicenter retrospective study of 78 distal MBO patients by Debourdeau et al[30], EUS-GBD was found to have similar technical and clinical success as compared with EUS-CDS after failed ERCP, raising the question whether EUS-GBD can be directly approached instead of EUS-CDS after unsuccessful ERCP. Another study by Ishiwatari et al[31] showed that adding antegrade stenting to EUS-HGS may prolong the time to recurrent biliary obstruction when compared with conventional EUS-HGS. Lastly, it remains to be seen whether EUS-BD can entirely replace ERCP as the modality of choice for patients with distal MBO[32,33]. Therefore, we can conclude that out of the latest advancements of EUS[34], EUS-BD represents one of the most important innovations with intriguing future implications.

CONCLUSION

The updated meta-analysis by Peng et al[12] reinforces the knowledge of high technical and clinical success of EUS-BD in patients with MBO. The adverse events and reintervention rates also appear to be similar to other previous meta-analyses. Usage of ECE-LAMS, with its single-step procedure benefit, has greatly enhanced the uptake of EUS procedures by the endoscopists. Future large-scale studies would be important to strengthen the role of EUS-BD in this patient population, especially due to the potential of even replacing ERCP as the first-line therapeutic option.