CLINICAL STUDY

Suprapapillary versus Transpapillary Stent Placement for Malignant Biliary Obstruction: Which Is Better? Jeong-Hyun Jo, MD, and Byeong-Ho Park, MD, PhD

ABSTRACT Purpose: To compare the complications, stent patency, and patient survival with self-expandable metal stents (SEMSs) placed above or across the sphincter of Oddi in malignant biliary obstruction. Materials and Methods: From January 2008 to December 2012, 155 patients were treated with percutaneous transhepatic SEMS placement. Seventy-four patients underwent suprapapillary stent placement (group A), and 81 patients underwent transpapillary stent placement (group B). Complications rates, stent patency, and patient survival were evaluated and analyzed for potential predictors. Results: In group A, 68 covered and 28 uncovered SEMSs were placed, and, in group B, 78 covered and 19 uncovered SEMSs were placed. Thirty-six stent-related early complications were observed in a total of 154 patients (23.4%): pancreatitis (n ¼ 23), cholangitis (n ¼ 12), and cholecystitis (n ¼ 1). The early complication rates for groups A and B were 14.9% (11 of 74) and 31.3% (25 of 80), respectively (P ¼ .016). Pancreatitis occurred in three patients (4.1%) in group A and 20 patients (25.0%) in group B (P ¼ .001). Stent location was a single independent predictor of pancreatitis (P o .001). Stent occlusions by tumor growth was more frequently observed in group A than in group B (P ¼ .007), whereas stent occlusion by sludge incrustation was more frequently found in group B than in group A (P ¼ .007). There was no significant difference in cumulative stent patency (P ¼ .401) or patient survival (P ¼ .792) between groups. Conclusions: To decrease the incidence of pancreatitis, suprapapillary placement of SEMSs is recommended for malignant biliary obstruction, but not in the lower 2 cm of the common bile duct.

ABBREVIATIONS CBD = common bile duct, PTBD = percutaneous transhepatic biliary drainage, SEMS = self-expandable metal stent

In patients with obstructive jaundice caused by unresectable malignant tumors, such as pancreatic cancer, cholangiocarcinoma, and gallbladder cancer, percutaneous or endoscopic self-expandable metal stent (SEMS) insertion has become a standard palliative treatment. Most previous studies have evaluated the effectiveness of the procedure with regard to patient-related characteristics (tumor type/stage and obstruction level) or stent-related From the Department of Radiology, Dong-A University, College of Medicine, 26, Daesingongwon-ro, Seo-gu, Busan 602-715, Republic of Korea. Received July 2, 2014; final revision received November 13, 2014; accepted November 27, 2014. Address correspondence to B.-H.P.; E-mail: [email protected] Neither of the authors has identified a conflict of interest. From the SIR 2014 Annual Meeting. & SIR, 2015 J Vasc Interv Radiol 2015; 26:573–582 http://dx.doi.org/10.1016/j.jvir.2014.11.043

characteristics (covered or uncovered, covering material, self- or balloon-expanding, and stainless steel or nitinol composition). Although there is a consensus among interventional radiologists that a safety margin of at least 2 cm should be left at each end of the upper and lower margins of the stricture to prevent tumor growth (1), controversy exists about the need to place the stent across the sphincter of Oddi located in the papilla of Vater when the tumor spares that region and does not obstruct the lower 2 cm of the common bile duct (CBD). Only a few reports (1–5) with SEMSs have compared efficiency between suprapapillary and transpapillary methods of stent placement for the palliation of malignant biliary obstruction. In terms of the incidence of cholangitis, the selection of a suprapapillary versus a transpapillary method of SEMS placement is under debate (2–4). Some authors suggested that the patency of a SEMS was not influenced by its location (1,5). The aim of the present study was to compare the complications, stent patency,

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and patient survival associated with SEMS placement above versus across the sphincter of Oddi in malignant biliary obstruction.

MATERIALS AND METHODS

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The clinical data, biologic data, imaging studies, and interventional radiologic procedures were analyzed by two independent radiologists. Data were recorded for the following variables: stent-related early and late complications, duration of stent patency, and patient survival time.

Patient Population Of patients who had inoperable malignant biliary obstruction or rejected surgery for malignant biliary obstruction (Fig 1), 155 patients (85 men and 70 women; mean age, 75 y; age range, 41–98 y) who underwent percutaneous transhepatic SEMS placement in our institution between January 2008 and November 2012 were included in this retrospective study. Institutional review board approval and a waiver of informed consent were obtained for this study. Causes of biliary obstruction were as follows: cholangiocarcinoma (n ¼ 57), pancreatic carcinoma (n ¼ 49), gallbladder cancer (n ¼ 14), metastatic carcinoma from a variety of primary sites (involving metastatic lymphadenopathy, n ¼ 28), and other causes (n ¼ 7). Forty-five patients had lesions involving the proximal bile ducts (hilar lesions), and 110 patients had lesions of the middle and distal bile ducts (nonhilar lesions). For analysis, the patients were divided into two groups according to the location of the distal end of the stent, ie, whether it crossed the ampulla of Vater. In group A, the distal end of the stent always lay above the sphincter of Oddi (suprapapillary location; Fig 2). In group B, the distal end of the stent protruded into the duodenum, less than 15 mm below the papilla (transpapillary location; Fig 3). There were 74 patients in group A and 81 in group B. Details of patient characteristics are presented in Table 1.

Procedure and Device A total of 193 SEMSs were implanted in 155 patients. Two or more SEMSs were inserted in 35 patients each. Of these patients, 32 with tumor involving the hepatic hilum received stents in X-, Y-, or T-configurations to facilitate bile drainage. Based on the morphologic findings of cholangiograms obtained before stent placement, covered stents were directly inserted to tumors involving the biliary tree. In cases of extrinsic biliary compression, uncovered stents were inserted. In group A, 68 covered and 28 uncovered SEMSs were placed, whereas, in group B, 78 covered and 19 uncovered SEMSs were placed. Stent placement was performed in a two-step procedure: percutaneous transhepatic biliary drainage (PTBD) as the first step and stent deployment as the second step. A standard PTBD procedure through a 21-gauge Chiba needle under fluoroscopic and/or ultrasound (US) guidance was performed on all patients, always under local anesthesia along with mild intravenously administered sedation and analgesia. The access site (right or left lobe) was chosen according to the extent of the tumor on preprocedural imaging. Two days after PTBD, we obtained tube cholangiograms to evaluate the exact disease extent and to locate the biliary stent. The median time interval between initial biliary drainage and stent placement was 12 days (range, 1–413 d; mean, 26 d). For a lesion with a distal margin located within the lower 2

Figure 1. Patient selection protocol of transhepatic biliary stent insertion.

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Figure 2. Images from a 77-year-old man with mid-CBD cancer. (a) Segmental obstruction of the midportion of the CBD (arrow) with disease sparing the distal CBD. (b) By means of the suprapapillary placement method, the lesion was successfully palliated. Arrows point to the ends of the upper and lower margins of the stent.

Figure 3. Images from a 77-year-old woman with distal CBD cancer. (a) Near-total obstruction of the CBD is seen (arrow). (b) Percutaneous transhepatic cholangiogram demonstrated the good passage of contrast materials to the duodenum 2 days after transpapillary stent placement. Note the distal end (black arrow) of the stent that crossed the ampulla of Vater (white arrow).

cm of the CBD, a stent was placed across the ampulla of Vater (transpapillary method). When a tumor did not involve the lower 2 cm of the CBD, a stent was placed above the ampulla of Vater (suprapapillary method). Stent length was selected to cover the whole obstructive lesion and a part of the normal biliary tree, at least 2 cm below and above the lesion to avoid tumor overgrowth.

Only when the stent could not be passed through the obstructed lesion in the CBD was predilation of the obstruction site performed with a 4-mm-diameter balloon. To permit bile drainage and check stent function, an 8.5-F drainage catheter was placed after stent placement. The catheter tip was placed immediately proximal to the stent. When follow-up cholangiography

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Table 1 . Patient Characteristics (N ¼ 155) Characteristic

Group A (n ¼ 74)

Sex (M/F)

Group B (n ¼ 81)

44/30

42/39

74.2 ⫾ 9.9

71.3 ⫾ 11.0

Cause of obstruction Cholangiocarcinoma

35

22

Pancreatic cancer

10

39

Gallbladder cancer Metastatic carcinoma

9 16

5 12

Other

4

3

32

13

42

68

Mean age (y) ⫾ SD

Level of obstruction Hilum Common bile duct SD ¼ standard deviation.

performed within 5 days after stent placement showed good passage of contrast material through the stent into the CBD and duodenum, the drainage catheter was removed without clamping.

Definitions Complications included only stent-related ones except for stent dysfunction defined as stent migration and stent fracture. They were classified as immediate (o 24 h after stent placement), early (r 30 d), or late (4 30 d). Stentrelated complications, such as cholangitis, cholecystitis, and pancreatitis, were diagnosed by clinical signs and symptoms along with laboratory test results (white blood cell count and C-reactive protein level). Stent-related cholangitis was defined as a condition that included fever exceeding 381C, leukocytosis, and an elevated C-reactive protein level associated with abdominal pain, without other evidence of infections (2). Pancreatitis was diagnosed according to consensus criteria: new or worsening abdominal pain persisting for at least 24 hours and requiring analgesics after SEMS placement with an increase in serum amylase or lipase level greater than three times the upper limit of normal (6). The duration of stent patency was defined as the interval between stent placement and the recurrence of obstructive jaundice. If obstruction was not evident during a patient’s life, stent patency was considered equal to the patient’s survival. Patency after repeat intervention was not included in the analysis. Technical success was defined as the successful deployment of the stent in the appropriate position resulting in drainage of the stented bile ducts.

Follow-up and Statistical Analysis We evaluated serum levels of bilirubin, liver enzymes (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and γ-glutamyl transpeptidase), and pancreatic enzymes (amylase, lipase) before percutaneous drainage and before and after stent deployment. When a patient presented with distinct jaundice or higher bilirubin levels during follow-up, computed tomography (CT) with

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or without US examination was performed for tumor/stent evaluation. When CT revealed stent obstruction, PTBD was conducted. When the occlusion level was detected mainly at the proximal and/or distal end of the stent on CT, it was considered as tumor overgrowth. However, when the occlusion level was limited to the inside of the stent lumen, it was considered as tumor ingrowth. Also, stent obstruction by sludge incrustation had to be excluded. To distinguish between stent occlusion by sludge incrustation and that by tumor growth, a balloon catheter (5  40 mm) was used when PTBD was performed for the treatment of stent obstruction. An inflated balloon was initially inserted into the occluded stent lumen over the wire and carefully moved up and down to remove any debris in the stent. If the fluoroscopic images did not show intraluminal clearance of the stent, tumor growth was suspected. The cause of stent obstruction was determined based on cholangiographic findings and balloon manipulation for the obstructed lesion, as well as CT images. Statistical differences in the number/cause of obstruction and the number of complications between the two groups was compared using the χ2 test. The cumulative stent patency rate and the patient survival rate were estimated using the Kaplan–Meier technique with lifetable analyses. Univariate log-rank analysis was used to compare differences in stent patency and patient survival between the two groups. We supposed that potential predictors such as age, sex, obstruction level and cause, stent location, stent configuration (simple placement in the CBD vs X-, Y-, or T-configured bilateral placement), and stent type (covered vs uncovered) would influence complication rate, stent patency, and patient survival. Logistic regression analysis was used to evaluate the probability of complications after SEMS placement. Cox proportional-hazards analysis was performed to evaluate potential predictors of stent patency and patient survival. The level of statistical significance was set at P o .05. All statistical analyses were conducted with SPSS software (version 19.0; IBM, Armonk, New York).

RESULTS Technical Success Failure of stent placement occurred in one patient (technical success rate, 99.4%). This patient with pancreatic cancer had poor stent expansion despite correct deployment. Although balloon dilation was performed after 8 days, the stent was not dilated. This case was excluded from follow-up for complications, stent patency, and patient survival. Two patients had migrated stent immediately after initial placement. An additional stent was used for successful drainage.

Complications Thirty-six stent-related early complications were observed in a total of 154 patients (23.4%): pancreatitis (n ¼ 23),

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cholangitis (n ¼ 12, unrelated to stent obstruction), and cholecystitis (n ¼ 1). All cases of pancreatitis and cholangitis occurred immediately after stent placement. Patients with pancreatitis showed a mean amylase level of 1,396 IU/L ⫾ 1,171 and a mean lipase level of 2,493 U/L ⫾ 2,240, which resolved completely within 7 days after conservative treatment. Also, patients with cholangitis were treated completely within 4 days after conservative therapy and antibiotic agent administration. Acute cholecystis developed in one patient at 5 days after stent placement in group A. This patient had tumor invasion of the cystic duct, and cholecystis resolved with antibiotic therapy. The comparisons of complications between groups A and B are presented in Table 2. The early complication rates were 14.9% (11 of 74) in group A and 31.3% (25 of 80) in group B (P ¼ .016). Pancreatitis occurred in three patients (4.1%) in group A and 20 patients (25.0%) in group B (P ¼ .001). In addition, we evaluated the probability of developing pancreatitis and cholangitis as potential predictors by using logistic regression analysis. As shown in Table 3, stent location alone was associated with the incidence of pancreatitis on univariate (P ¼ .001) and multivariate (P o .001) logistic regression analyses. However, there were no independent predictors of cholangitis (Table 4). When we retrospectively reviewed the radiologic images of each patient, stent dysfunction was found in five patients (3.2%). All five patients were in group B and underwent covered nitinol stent placement. Stent migration occurred in two patients with pancreatic head cancer at 5 and 132 days after stent placement, respectively. In the remaining patients, stent fractures developed only at the level of sphincter of Oddi. One case of stent fracture that occurred in a patient with distal cholangiocarcinoma was detected at 239 days after stent placement and showed stent obstruction by tumor overgrowth at 434 days after stent placement. Another case that occurred in a patient with distal cholangiocarcinoma was detected at 297 days after stent placement together with stent obstruction by tumor ingrowth and overgrowth. The third case that occurred in a patient with pancreatic head cancer was detected at 495 days after stent placement and showed no stent obstruction during the follow-up period. Table 2 . Comparison of Complications between the Suprapapillary (Group A) and Transpapillary (Group B) Groups

No. of complications Pancreatitis* Cholangitis† Cholecystitis‡

Group A (n ¼ 74)

Group B (n ¼ 80)

P Value

11 (14.9) 3 (4.1)

25 (31.3) 20 (25.0)

.016 .001

7 (9.5)

5 (6.3)

.283

1

0



Note–Values in parentheses are percentages. *Immediate. † Immediate; unrelated to stent obstruction. ‡ Because of the small number of patients, no meaningful statistical comparison could be performed.

Stent Patency and Patient Survival The number and causes of stent obstruction in the two groups are listed in Table 5. Stent occlusion developed in 53 of 154 patients (34.4%; mean time, 202 d ⫾ 159). Of the 53 patients, 33 had stent occlusion caused by tumor growth (62.3%) and 20 had stent occlusion caused by sludge incrustation. Stent occlusion occurred in 31 patients (41.9%; mean, 214 d ⫾ 152) in group A and in 22 patients (27.5%; mean, 186 d ⫾ 168) in group B (P ¼ .060). Stent occlusion caused by tumor growth occurred in 24 of 31 patients (77.4%) in group A and in nine of 22 patients (40.9%) in group B, whereas stent occlusion caused by sludge incrustation occurred in seven of 31 patients (22.6%) in group A and in 13 of 22 patients (59.1%) in group B (P ¼ .007). Cholangitis related to stent obstruction as a late complication occurred in 16 patients (30.2%). The mean time to occurrence of cholangitis was 288 days ⫾ 166. Cholangitis was caused by stent obstruction by sludge incrustation and tumor growth in 35% (seven of 20) and 27.3% (nine of 33) of patients, respectively (P ¼ .553). Cholangitis was found in seven patients (9.5%) in group A and nine patients (11.3%) in group B (P ¼ .716). The overall cumulative stent patency rates at 1, 3, 6, and 12 months were 92%, 82%, 65%, and 33%, respectively. The mean duration of stent patency was 275 days ⫾ 17. The cumulative stent patency rates at 1, 3, 6, and 12 months were 96%, 80%, 66%, and 29%, respectively, in group A, and 89%, 83%, 64%, and 39%, respectively, in group B. The mean durations of stent patency were 262 days ⫾ 22 in group A and 290 days ⫾ 27 in group B (P ¼ .401; Fig 4). Univariate Cox proportional-hazards analyses stratified by potential predictors of stent patency failed to reveal statistically significant differences. Age alone was associated with stent patency on multivariate analyses (Table 6). Seven patients died within 30 days, for a 30-day mortality rate of 4.5%. The causes of death were disease progression and poor clinical condition in all patients, and were not directly related to stent placement. The overall cumulative patient survival rates at 3, 6, and 12 months were 89%, 84%, and 62%, respectively. The mean survival time of the whole patient population was 394 days ⫾ 19. The cumulative patient survival rates at 3, 6, and 12 months were 89%, 85%, and 58%, respectively, in group A, and 90%, 84%, and 64%, respectively, in group B. The mean patient survival times were 384 days ⫾ 27 in group A and 400 days ⫾ 28 in group B (P ¼ .792; Fig 5). Although univariate Cox proportional-hazards analyses stratified by potential predictors of patient survival failed to reveal significant differences, age and sex were associated with survival on multivariate analysis (Table 7).

DISCUSSION Exact etiologic factors for the development of pancreatitis after SEMS placement are unknown. A high incidence of

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Table 3 . Univariate and Multivariate Logistic Regression Analyses of Variables Predicting after Stenting Pancreatitis Variable

n (%)

Univariate P Value

OR (95% CI) Age o Mean (75 y)

75 (48.7)

1

Z Mean (75 y)

79 (51.3)

0.849 (0.350–2.062)

Gender Male Female Obstruction level CBD Hilum

Multivariate

85 (55.2)

1

69 (44.8)

2.149 (0.868–5.321)

111 (72.1)

1

43 (27.9)

0.680 (0.235–1.963)

.098

.476

57 (37.0)

1

Pancreatic cancer

48 (31.2)

0.536 (0.184–1.556)

.251

Metastases Gallbladder cancer

28 (18.2) 14 (9.1)

0.450 (0.116–1.747) 0.288 (0.034–2.431)

.249 .253

7 (4.5)

0.625 (0.069–5.701)

.677

Others

74 (48.1)

1

Transpapillary

80 (51.9)

7.889 (2.235–27.846)

Stent configuration Simple placement in CBD Bilateral configuration

P Value

.718

Obstruction cause Cholangiocarcinoma

Stent location Suprapapillary

OR (95% CI)

1

120 (77.9)

1

34 (22.1)

0.484 (0.135–1.738)

Stent type Uncovered

24 (15.6)

1

Covered

130 (84.4)

4.685 (0.601-36.538)

.001

11.387 (3.023–42.895)

o .001

.266

.141

Note–The multivariate analysis was constructed by stepwise forward selection using maximum likelihood estimation. CBD ¼ common bile duct, CI ¼ confidence interval, OR ¼ odds ratio.

pancreatitis has been reported in patients without tumor involvement of the main pancreatic duct (7,8). Kawakubo et al (6) demonstrated that nonpancreatic cancer—mainly cholangiocarcinoma and lymph node metastases—is strongly associated with a high incidence of pancreatitis following endoscopic transpapillary SEMS placement. They thought that the incidence of pancreatitis was high because the main pancreatic duct is not completely obstructed and the distal pancreas is preserved in patients with nonpancreatic cancer. Because the patients in group B in the present study had an approximately 11.4 times greater risk of pancreatitis than those in group A, the incidence of pancreatitis (14.9%) is higher in the present study, which included 68.4% nonpancreatic cancer cases, than in previous studies (9–15) that included less than 40% nonpancreatic cancer cases (incidence rate of pancreatitis o 7%) and lower than in a study by Han et al (15) that included 78.4% nonpancreatic cancer cases (29%). We considered that nonpancreatic cancer is associated with a high incidence of pancreatitis. However, when causes of obstruction were subdivided into pancreatic and nonpancreatic cancers in the present study, there was no significant difference (P ¼ .569; not shown in Table 3) in the incidence of pancreatitis

between patients with pancreatic cancer and those with nonpancreatic cancer. Because mostly covered SEMSs (84.4%) were placed in the present study, another possible explanation may be that occlusion of the pancreatic ducts by the covering is a potential risk (16–19). However, no significant differences were observed between covered and uncovered SEMSs in the incidence of pancreatitis in two published meta-analyses (20,21) and or the present study. In addition, Kawakubo et al (6) stated that SEMSs with high axial force (defined as recovery force to ensure that the stent returns back straight after bending) are significantly correlated with a high incidence of pancreatitis. However, mechanical characteristics of SEMSs were not measured in the present study. Further studies on the causes and incidence of pancreatitis in patients who receive SEMS placement are warranted. In the present study, there were significant differences in causes of stent obstruction between the two groups. The main cause of stent obstruction were tumor growth in group A (17 with overgrowth, four with ingrowth, and four with both) and sludge incrustation in group B. Tumor growth and sludge incrustation are the two most common causes of stent obstruction as a late complication. Duodenobiliary reflux is one of the mechanisms of

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Table 4 . Univariate Logistic Regression Analyses of Variables Predicting Cholangitis after Stent Placement* Variable

No. of Pts. (%)

OR (95% CI)

P Value

Age o 75 y (below mean)

75 (48.7)

1

Z 75 y (above mean) Sex

79 (51.3)

2.704 (0.689–10.608)

Male Female Obstruction level CBD Hilum Obstruction cause

85 (55.2)

1

69 (44.8)

0.438 (0.112–1.717)

111 (72.1)

1

43 (27.9)

2.303 (0.664–7.985)

.154

.236

.189

Cholangiocarcinoma

57 (37.0)

1

Pancreatic cancer Metastases

48 (31.2) 28 (18.2)

0.567 (0.134–2.398) 0.315 (0.036–2.751)

.843 .440

Gallbladder cancer

14 (9.1)

0.654 (0.072–5.918)

.705

7 (4.5)

0.625 (0.069–5.701)

.999

Others Stent location Suprapapillary

74 (48.1)

1

Transpapillary Stent configuration

80 (51.9)

0.504 (0.141–1.797)

Simple placement in CBD Bilateral configuration Stent type

120 (77.9)

1

34 (22.1)

1.355 (0.339–5.414)

Uncovered

24 (15.6)

1

Covered

130 (84.4)

0.459 (0.113–1.871)

.291

.667

.278

Note–Although multivariate analysis was constructed by stepwise forward selection using maximum likelihood estimation, there was no variable reported, so no multivariate analysis was displayed. CBD ¼ common bile duct, CI ¼ confidence interval, OR ¼ odds ratio. n Immediate cholangitis unrelated to stent obstruction.

Table 5 . Details of Stent Obstruction Finding

Group A

Group B

P Value

Cases of obstruction Cause of obstruction

31 (41.9)

22 (27.5)

.060 .007

Tumor growth

24 (77.4)

9 (40.9)

Sludge

7 (22.6)

13 (59.1)

Note–Values in parentheses are percentages.

sludge incrustation including food debris (22,23). After stent insertion across the major papilla, the function of the sphincter of Oddi, which prevents reflux of food materials from the duodenum, is interrupted (24). A recent study that used a barium meal examination (23) showed that reflux of gastric and duodenal contents through SEMSs is a universal phenomenon and that, with the large caliber of the SEMS, the pressure gradient between the bile duct and the duodenum is lost, thereby promoting reflux of the duodenal contents. Although the obstruction rate was not significantly different between the two groups in the present study, there was a tendency toward more obstruction in group A (P ¼ .060). Statistical differences may be observed in a larger cohort study.

Okamoto et al (2) documented that stent placement across the main duodenal papilla is the most significant risk factor for cholangitis. Hatzidakis et al (3) found a statistically significant difference in incidences of cholangitis between the suprapapillary and transpapillary groups (33% vs 10%). Sol et al (4) reported that the occurrence of early (o30 d) infectious complications (cholangitis, cholecystitis, and liver abscess) after percutaneous SEMS placement was significantly associated with suprapapillary stent placement. However, we found no risk factors for the occurrence of cholangitis (unrelated to stent obstruction) as an early complication. In terms of baseline patient characteristics, a significant difference in the cause of biliary obstruction was found between the two groups in the present study. The most common causes were cholangiocarcinoma (47.3%) and pancreatic cancer (47.5%) in groups A and B, respectively, whereas pancreatic cancer was found in 13.5% of patients in group A and cholangiocarcinoma in 27.5% of patients in group B (P o .01). On the basis of this difference, it is possible that the cause of biliary obstruction influenced our results, such as immediate complications after SEMS placement, stent patency, and patient survival. However, there was no significant difference in the results if patients are stratified according to cause of biliary obstruction.

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Figure 4. Kaplan–Meier curves demonstrating cumulative stent patency in group A versus group B (P ¼ .401, log-rank analysis).

Table 6 . Univariate and Multivariate Cox Proportional-Hazards Analyses of Variables Predicting Stent Obstruction Univariate Variable

Multivariate

n (%) HR (95% CI)

P Value

HR (95% CI)

.780

1.62 (1.13–2.31)

.155

0.72 (0.52–1.03)

P Value

Age o Mean (75 y)

75 (48.7)

1

Z Mean (75 y) Gender

79 (51.3)

1.35 (0.97–1.87)

Male Female Obstruction level CBD Hilum Obstruction cause

85 (55.2)

1

69 (44.8)

0.78 (0.56–1.10)

111 (72.1)

1

43 (27.9)

0.99 (0.68–1.44)

1

1

.966

Cholangiocarcinoma

57 (37.0)

1

Pancreatic cancer Metastases

48 (31.2) 28 (18.2)

0.63 (0.24–1.63) 0.85 (0.37–1.96)

.337 .705

Gallbladder cancer

14 (9.1)

1.10 (0.53–2.27)

.791

7 (4.5)

0.69 (0.40–1.18)

.178

Others Stent location Suprapapillary

74 (48.1)

1

Transpapillary Stent configuration

80 (51.9)

1.27 (0.91–1.78)

Simple placement in CBD Bilateral configuration Stent type

120 (77.9)

1

34 (22.1)

0.83 (0.54–1.28)

Uncovered

24 (15.6)

1

Covered

130 (84.4)

1.49 (0.89–2.51)

.008

.156

.399

.132

Note.–The multivariate analysis was constructed by stepwise forward selection using maximum likelihood estimation. CBD ¼ common bile duct, CI ¼ confidence interval, HR ¼ hazard ratio.

.070

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Figure 5. Kaplan–Meier curves demonstrating cumulative patient survival in group A versus group B (P ¼ .792, log-rank analysis). Table 7 . Univariate and Multivariate Cox Proportional-Hazards Analyses Identifying Independent Survival Predictors Variable

n (%)

Univariate HR (95% CI)

Multivariate P Value

HR (95% CI)

.032

1.62 (1.21–2.18)

.109

0.73 (0.55–0.97)

P Value

Age o Mean (75 y)

75 (48.7)

1

Z Mean (75 y) Gender

79 (51.3)

1.35 (1.03–1.79)

Male Female Obstruction level CBD Hilum Obstruction cause

85 (55.2)

1

69 (44.8)

0.80 (0.60–1.05)

111 (72.1)

1

43 (27.9)

0.88 (0.64–1.20)

1

1

.416

Cholangiocarcinoma

57 (37.0)

1

Pancreatic cancer Metastases

48 (31.2) 28 (18.2)

0.53 (0.24–1.15) 0.84 (0.42–1.66)

.107 .607

Gallbladder cancer

14 (9.1)

1.09 (0.59–2.00)

.784

7 (4.5)

0.67 (0.43–1.05)

.083

Others Stent location Suprapapillary

74 (48.1)

1

Transpapillary Stent configuration

80 (51.9)

1.14 (0.87–1.50)

Simple placement in CBD Bilateral configuration Stent type

120 (77.9)

1

34 (22.1)

0.78 (0.55–1.11)

Uncovered

24 (15.6)

1

Covered

130 (84.4)

1.43 (0.93–2.19)

.001

.339

.165

.099

Note.–The multivariate analysis was constructed by stepwise forward selection using maximum likelihood estimation. CBD ¼ common bile duct, CI ¼ confidence interval, HR ¼ hazard ratio.

.029

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Suprapapillary vs Transpapillary Stents for Malignant Biliary Obstruction

Two meta-analyses (20,21) reported that covered SEMSs decreased tumor ingrowth but increased stent migration and tumor overgrowth. One of the two (20) revealed a significantly longer patency duration in the covered SEMS group, but the other (21) did not appear to show longer patency. In the present study, the stent type (covered vs uncovered stent) was not a significant factor for stent patency, patient survival, or complications such as pancreatitis and cholangitis. However, it is noteworthy that all stent dysfunctions occurred in group B patients treated with covered stents. No statistical comparisons of stent dysfunctions were made in patients who underwent covered versus uncovered stent placement because of the small number of cases. There was no statistically significant difference in stent patency and patient survival between the groups in the present study. As for stent patency, the results of this study are supported by previous studies (1,5,25) with SEMS placement by a percutaneous transhepatic approach. To the best of our knowledge, there have been few studies of comparative patient survival in suprapapillary and transpapillary SEMS placement groups. The present study has some limitations. First, a significant difference in the causes of biliary obstruction was found between the two groups. Because all stents were placed with one of two methods (suprapapillary vs transpapillary) in accordance with the location of the distal margin of the obstruction relative to the ampulla of Vater, the two groups are inherently different. Second, this was not a prospective study. Clinical data collected during follow-up periods were retrospective in nature, and followup at specific time intervals was not completed in some patients. Third, in most patients, no pathologic diagnosis was established to confirm the cause of stent obstruction. In conclusion, transpapillary placement of SEMSs for the palliation of malignant biliary obstruction may increase the risk of pancreatitis, although no significant differences in the incidence of cholangitis, stent patency, or patient survival between the suprapapillary and transpapillary placement groups were found. Therefore, it is believed that suprapapillary SEMS placement should be considered in patients with malignant biliary obstruction when the tumor is more than 2 cm from the ampulla of Vater. In addition, there is a need to pay attention to the possibility of stent dysfunctions, such as migration and fracture, in patients who undergo transpapillary placement of covered SEMSs. Further randomized control studies are needed to confirm the findings of the present study.

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Jo and Park



JVIR

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Suprapapillary versus transpapillary stent placement for malignant biliary obstruction: which is better?

To compare the complications, stent patency, and patient survival with self-expandable metal stents (SEMSs) placed above or across the sphincter of Od...
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