Early detection of pancreatic cancer by comprehensive serum miRNA sequencing with automated machine learning.

BACKGROUND: Pancreatic cancer is often diagnosed at advanced stages, and early-stage diagnosis of pancreatic cancer is difficult because of nonspecific symptoms and lack of available biomarkers. METHODS: We performed comprehensive serum miRNA sequencing of 212 pancreatic cancer patient samples from 14 hospitals and 213 non-cancerous healthy control samples. We randomly classified the pancreatic cancer and control samples into two cohorts: a training cohort (N = 185) and a validation cohort (N = 240). We created ensemble models that combined automated machine learning with 100 highly expressed miRNAs and their combination with CA19-9 and validated the performance of the models in the independent validation cohort. RESULTS: The diagnostic model with the combination of the 100 highly expressed miRNAs and CA19-9 could discriminate pancreatic cancer from non-cancer healthy control with high accuracy (area under the curve (AUC), 0.99; sensitivity, 90%; specificity, 98%). We validated high diagnostic accuracy in an independent asymptomatic early-stage (stage 0-I) pancreatic cancer cohort (AUC:0.97; sensitivity, 67%; specificity, 98%). CONCLUSIONS: We demonstrate that the 100 highly expressed miRNAs and their combination with CA19-9 could be biomarkers for the specific and early detection of pancreatic cancer.

Endoscopic placement of covered versus uncovered self-expandable metal stents for palliation of malignant gastric outlet obstruction.

OBJECTIVE: Stenting is an established endoscopic therapy for malignant gastric outlet obstruction (mGOO). The choice of stent (covered vs uncovered) has been examined in prior randomised studies without clear results. DESIGN: In a multicentre randomised prospective study, we compared covered (CSEMS) with uncovered self-expandable metal stents (UCSEMS) in patients with mGOO; main outcomes were stent dysfunction and patient survival, with subgroup analyses of patients with extrinsic and intrinsic tumours. RESULTS: Overall survival was poor with no difference between groups (probability at 3 months 49.7% for covered vs 48.4% for uncovered stents; log-rank for overall survival p=0.26). Within that setting of short survival, the proportion of stent dysfunction was significantly higher for uncovered stents (35.2% vs 23.4%, p=0.01) with significantly shorter time to stent dysfunction. This was mainly relevant for patients with extrinsic tumours (stent dysfunction rates for uncovered stents 35.6% vs 17.5%, p<0.01). Subgrouping was also relevant with respect to tumour ingrowth (lower with covered stents for intrinsic tumours; 1.6% vs 27.7%, p<0.01) and stent migration (higher with covered stents for extrinsic tumours: 15.3% vs 2.5%, p<0.01). CONCLUSIONS: Due to poor patient survival, minor differences between covered and uncovered stents may be less relevant even if statistically significant; however, subgroup analysis would suggest to use covered stents for intrinsic and uncovered stents for extrinsic malignancies.

Comparison of the Diagnostic Performance of Newly Designed 21-Gauge and Standard 22-Gauge Aspiration Needles in Patients with Solid Pancreatic Masses.

BACKGROUND: Although endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has been widely used for the diagnosis of pancreatic tumors, the ability to obtain adequate pancreatic tumor tissue needs to be improved. AIMS: This study was performed to compare a newly designed 21-gauge needle (EUS Sonopsy CY; Hakko Medical, Nagano, Japan) and a standard 22-gauge needle for tissue sampling of solid pancreatic masses. METHODS: Consecutive patients with solid pancreatic masses who underwent EUS-FNA with either the EUS Sonopsy CY or the 22-gauge needle from June 2014 to December 2016 were enrolled. The primary outcome was comparison of the diagnostic yield of the FNA samples. The secondary outcomes were comparison of technical success, diagnostic ability for malignancy, and complications. RESULTS: A total of 93 patients (40.9% female; mean age, 70.1 years) underwent EUS-FNA with the EUS Sonopsy CY (n = 47) or the standard 22-gauge needle (n = 46). The technical success rate was 100% in both groups, and the overall diagnostic accuracy for malignancy was similar between the groups (100% in the EUS Sonopsy CY group vs. 95.7% in the 22-gauge needle group, P = 0.242). Nevertheless, the EUS Sonopsy CY resulted in significantly higher scores for cellularity (P = 0.006) and lower scores for blood contamination (P < 0.001). The procedure-related complication rate was comparable between the groups (P = 0.148). CONCLUSIONS: The EUS Sonopsy CY provided higher-quality specimens for histological evaluation in terms of both sample cellularity and blood contamination for the diagnosis of solid pancreatic masses. TRIAL REGISTRATION: The study was registered in a clinical trial registry, No. UMIN000032598.

Clinical efficacy and safety of endoscopic ultrasound-guided gallbladder drainage replacement of percutaneous drainage: A multicenter retrospective study.

OBJECTIVES: Percutaneous transhepatic gallbladder drainage (PTGBD) is widely used for patients with acute cholecystitis. There are little data on the efficacy and safety of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) replacement of PTGBD in patients who cannot undergo cholecystectomy. METHODS: This multicenter retrospective study in Japan reviewed records of patients who underwent EUS-GBD to replace PTGBD between January 2010 and December 2017. Outcomes evaluated included technical success, defined as successful stent placement between the gastrointestinal lumen and the gallbladder; clinical success, defined as subsequent removal of the percutaneous catheter; adverse events; and stent patency. RESULTS: EUS-GBD was performed in 21 patients (14 women, mean age 77.5 ± 8.0 years) to replace PTGBD that had been instituted for acute cholecystitis (n = 19) or obstructive jaundice (n = 2). Technical success was achieved in 19 (90.5%). The median period from PTGBD placement to EUS-GBD was 11 days (range, 6-68 days). The mean procedure time was 19.5 ± 5.1 min. No early adverse events were observed. There were three late adverse events, distal stent migration in two cases and stent occlusion causing recurrent cholecystitis in one patient. Reintervention was required in two patients. The percutaneous catheter was removed after EUS-GBD in 17 patients at a median of 7 days (range, 2-20 days). The duration of stent patency was 139 days (range, 8-664 days). CONCLUSIONS: Where ongoing gallbladder drainage is required, conversion from PTGBD to EUS-GBD is a feasible, effective, and safe technique for patients who cannot undergo cholecystectomy.

Comparison of the efficacy and safety of endoscopic ultrasound-guided choledochoduodenostomy and hepaticogastrostomy for malignant distal biliary obstruction: Multicenter, randomized, clinical trial.

BACKGROUND AND AIM: Endoscopic ultrasound-guided biliary drainage (EUS-BD) can be carried out by two different approaches: choledochoduodenostomy (CDS) and hepaticogastrostomy (HGS). We compared the efficacy and safety of these approaches in malignant distal biliary obstruction (MDBO) patients using a prospective, randomized clinical trial. METHODS: Patients with malignant distal biliary obstruction after failed endoscopic retrograde cholangiopancreatography were randomly selected for either CDS or HGS. The procedures were carried out at nine tertiary centers from September 2013 to March 2016. Primary endpoint was technical success rate, and the noninferiority of HGS to CDS was examined with a one-sided significance level of 5%, where the noninferiority margin was set at 15%. Secondary endpoints were clinical success, adverse events (AE), stent patency, survival time, and overall technical success including alternative EUS-BD procedures. RESULTS: Forty-seven patients (HGS, 24; CDS, 23) were enrolled. Technical success rates were 87.5% and 82.6% in the HGS and CDS groups, respectively, where the lower limit of the 90% confidence interval of the risk difference was -12.2% (P = 0.0278). Clinical success rates were 100% and 94.7% in the HGS and CDS groups, respectively (P = 0.475). Overall AE rate, stent patency, and survival time did not differ between the groups. Overall technical success rates were 100% and 95.7% in the HGS and CDS groups, respectively (P = 0.983). CONCLUSIONS: This study suggests that HGS is not inferior to CDS in terms of technical success. When one procedure is particularly challenging, readily switching to the other could increase technical success.

Outcomes of endoscopic biliary drainage in pancreatic cancer patients with an indwelling gastroduodenal stent: a multicenter cohort study in West Japan.

BACKGROUND AND AIMS: Gastroduodenal and biliary obstruction may occur synchronously or asynchronously in advanced pancreatic cancer, and endoscopic double stent placement may be required. EUS-guided biliary drainage (EUS-BD) often is performed after unsuccessful placement of an endoscopic transpapillary stent (ETS), and EUS-BD may be beneficial in double stent placement. This retrospective multicenter cohort study compared the outcomes of ETS placement and EUS-BD in patients with an indwelling gastroduodenal stent (GDS). METHODS: We recorded the clinical outcomes of patients at 5 tertiary-care medical centers who required biliary drainage after GDS placement between March 2009 and March 2014. RESULTS: Thirty-nine patients were included in this study. Patients' mean age was 68.5 years; 23 (59.0%) were men. The GDS overlay the papilla in 23 patients (59.0%). The overall technical success rate was significantly higher with EUS-BD (95.2%) than with ETS placement (56.0%; P < .01). Furthermore, the technical success rate was significantly higher with EUS-BD (93.3%) than with ETS placement (22.2%; P < .01) when the GDS overlies the papilla. The overall clinical success rate of EUS-BD also was significantly higher than for ETS placement (90.5% vs 52.0%, respectively; P = .01), and there was no significant difference in the incidence of adverse events (ETS, 32.0% vs EUS-BD, 42.9%; P = .65). CONCLUSION: Endoscopic double stent placement with EUS-BD is technically and clinically superior to ETS placement in patients with an indwelling GDS. EUS-BD should be considered the first-line treatment option for patients with an indwelling GDS that overlies the papilla. ETS placement remains a reasonable alternative when the papilla is not covered by the GDS.

Multicenter prospective evaluation study of endoscopic ultrasound-guided hepaticogastrostomy combined with antegrade stenting (with video).

BACKGROUND AND AIM: Endoscopic ultrasonography-guided hepaticogastrostomy (EUS-HGS) is often indicated for advanced stage patients. Therefore it is important to prevent adverse events associated with EUS-HGS procedures and obtain long stent patency. EUS-guided antegrade stenting (AS) has been developed as an advanced technique. Thus, to prevent adverse events and achieve long stent patency, EUS-AS combined with EUS-HGS (EUS-HGAS) has been reported. The aim of the present study was to evaluate the technical feasibility and efficacy of EUS-HGAS in a multicenter, prospective study. METHODS: This prospective study was carried out at each hospital of the Therapeutic Endoscopic Ultrasound Group. Primary endpoint of this multicenter prospective study was stent patency of EUS-HGAS. RESULTS: A total of 49 patients were enrolled. Technical success rate of EUS-HGS was 95.9% (47/49). EUS-AS failed in five patients because the guidewire could not be advanced into the intestine across the bile duct obstruction site. Therefore, EUS-HGAS was successfully carried out in 40 patients (technical success rate: 85.7%). Median overall survival was 114 days. Median stent patency including stent dysfunction and patient death was 114 days. In contrast, mean stent patency was 320 days. Adverse events were seen in 10.2% (5/49) of cases. Hyperamylasemia was seen in four patients, and bleeding was seen in one patient. CONCLUSIONS: The present study is the first to evaluate EUS-HGAS. EUS-HGAS has clinical benefit for obtaining long stent patency and avoiding adverse events, although the possibility of acute pancreatitis as a result of obstruction of the orifice of the pancreatic duct must be considered.

Needle Tract Seeding: An Overlooked Rare Complication of Endoscopic Ultrasound-Guided Fine-Needle Aspiration.

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has been widely used for diagnosis of both inflammatory and tumor lesions located in and adjacent to the gastrointestinal tract. EUS-FNA has been considered to be a safe technique with few complications, as shown in recent review articles in which EUS-FNA-related morbidity and mortality rates were reported to be <1%. It should be noted, however, that needle tract seeding, although uncommon, can occur after diagnostic EUS-FNA and that this complication affects the prognosis of patients. Although an accurate value for the frequency of needle tract seeding caused by EUS-FNA has not been reported, the numbers of case reports on needle tract seeding have been rapidly increasing, especially in Japan. These case reports regarding EUS-FNA-related needle tract seeding prompted us to reevaluate the safety of EUS-FNA because this complication may have a significant influence on patients' prognoses. In this review, we summarize the clinical features and outcomes of needle tract seeding after EUS on the basis of the previously reported cases and provide useful information to prevent and reduce this serious complication.

The Feasibility of 18-mm-Diameter Colonic Stents for Obstructive Colorectal Cancers.

OBJECTIVES: This study aimed to evaluate the characteristics and the feasibility of 18-mm-diameter stents for obstructive colorectal cancer, comparing the clinical courses with 22- mm-diameter stents. METHODS: We retrospectively compared 33 consecutive cases treated with 18-mm-diameter stents (bridge to surgery [BTS] in 25, palliative therapy [PAL] in 8) with 27 consecutive cases treated with 22-mm-diameter stents (BTS in 21, PAL in 6) for obstructive colorectal cancer between May 2013 and November 2015 in our institution. RESULTS: There were no significant differences between the 18-mm and 22-mm groups in technical success rates (97 and 96%, respectively) and clinical success rates (100 and 100%, respectively). As a BTS, the rates of complications and stoma formation were not significantly different between groups. For PAL, although the rates of complications and stent patency were similar, stent occlusion occurred in 1 patient (12.5%) in the 18-mm group. CONCLUSIONS: The 18-mm-diameter stents were similarly effective when compared with 22-mm-diameter stents. Because 18-mm-diameter stents are easy to handle and produce less mechanical stress, they have the potential to decrease the perforation rate and mitigate the stent's impact on the tumors. 18-mm-diameter stents can be useful and safe, especially as a BTS.

Diagnostic performance of a new endoscopic scraper for malignant biliary strictures: a multicenter prospective study.

BACKGROUND AND AIMS: The efficacy of ERCP for histologic diagnosis of malignant biliary strictures is disappointingly low. The aim of this study was to investigate the diagnostic performance of a newly developed endoscopic device with scraping loops in combination with conventional biopsy forceps. METHODS: We performed a multicenter single-arm prospective study. Between February 2013 and December 2014, 123 patients with suspected malignant biliary strictures were enrolled in the study. The new device and conventional biopsy forceps were applied for histologic diagnosis by ERCP. The primary outcome was to evaluate cancer detectability by biopsy forceps, the new device, and their combined use. RESULTS: Of the 123 patients, 119 were diagnosed with a malignant stricture. Sufficient samples were collected in 83.7% (103/123), 93.5% (115/123), and 95.9% (118/123) of patients using biopsy forceps, the new device, and their combination, respectively. Cancer detectability of forceps biopsy, the new device, and their combination were 51.3% (61/119), 64.7% (77/119), and 74.8% (89/119), respectively. The new device had a significantly higher sample yield and cancer detectability than biopsy forceps (P < .01 and P = .018, respectively, McNemar test). Complementary use of the new device with biopsy forceps demonstrated a significantly additive effect in both sample yield and cancer detection (P < .01 each, McNemar test). The new device detected 48.3% (28/58) of cancers that were not diagnosed as malignant by biopsy forceps. CONCLUSIONS: The new endoscopic scraper demonstrated a large sample yield and high cancer detectability. It could be a first-line tissue-sampling device for biliary strictures. (University Hospital Medical Information Network Clinical Trial Registry [UMIN-CTR] (http://www.umin.ac.jp/ctr/index.htm) registration number: UMIN000009895.).

Evaluation of Early-phase Biodistribution in 123I-ioflupane SPECT.

It is reported that pharmacokinetics after intravenous injection of 123I-ioflupane may reflect cerebral blood flow. In this study, the early-phase pharmacokinetics of 123I-ioflupane in 10 healthy volunteers was analyzed over time using dynamic single-photon emission computed tomography (SPECT) immediately after intravenous injection. We also examined the correlation between the 123I-IMP imaging and the 123I-ioflupane early-phase image for 14 cases in which both dopamine transporter (DaT) imaging by 123I-ioflupane and cerebral blood flow imaging by 123I-IMP were performed on the same camera. The time-activity curve between cerebellum (CBL) area and each area of anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA) showed distribution characteristics similar to 123I-IMP from immediately after intravenous injection until 20 minutes after administration, and there was no conspicuous washout. The regression line and the correlation coefficient of the Z-score of three-dimensional stereotactic surface projections (3DSSP) (decrease) of the early-phase imaging of 123I-ioflupane and the 123I-IMP imaging are y=0.7546x+0.3562, r=0.8169 (P<0.01) at 0-10 minutes of 123I-ioflupane, and y=0.7412x+0.3027, r=0.8280 (P<0.01) at 0-15 minutes of 123I-ioflupane, and y=0.7400x+0.2456, r=0.8449 (P<0.01) at 0-20 minutes of 123I-ioflupane, showing a strong correlation at all timings. Therefore, 123I-ioflupane early-phase pharmacokinetics after intravenous showed distribution characteristics similar to 123I-IMP, indicating the possibility that early images may be useful in a clinical practice.

Factors predicting through-the-scope gastroduodenal stenting outcomes in patients with gastric outlet obstruction: a large multicenter retrospective study in West Japan.

BACKGROUND AND AIMS: Endoscopic gastroduodenal stenting for malignant gastric outlet obstruction recently has become more effective, but the factors that predict gastroduodenal stenting outcomes are poorly defined. This multicenter retrospective cohort study evaluated the clinical outcomes of gastroduodenal stenting in malignant gastroduodenal obstruction and identified factors predicting clinical ineffectiveness, stent dysfunction, and adverse events. METHODS: All consecutive patients with malignant gastroduodenal obstruction who underwent through-the-scope gastroduodenal stenting from 2009 to 2014 at 4 tertiary-care medical centers were identified. Clinically ineffective stenting was defined as symptom recurrence and a gastric outlet obstruction scoring system (GOOSS) score <2. RESULTS: Of the 278 patients (mean age ± standard deviation [SD] 71.7 ± 11.4 years), 121 (43.5%) and 87 (31.3%) had pancreatic and gastric cancer, respectively. Technical success was achieved in 277 patients (99.6%). GOOSS scores rose from 0.5 ± 0.6 to 2.6 ± 0.8. Stenting was ineffective in 32 patients (12.6%). Stent dysfunction that caused symptom recurrence during follow-up developed in 46 patients (16.6%). Adverse events occurred in 49 patients (17.7%). Three or more stenosis sites (odds ratio [OR] = 6.11; P < .01) and Karnofsky performance scores ≤50 (OR = 6.63; P < .01) predicted clinical ineffectiveness. Karnofsky performance scores ≤50 predicted stent dysfunction (hazard ratio [HR] = 3.63; P < .01). Bile duct stenosis (HR = 9.55; P = .02) and liver metastasis (HR = 9.42; P < .01) predicted stent overgrowth. Covered stent predicted stent migration (HR = 12.63; P < .01). Deployment of 2 stents predicted perforation (HR = 854.88; P < .01). CONCLUSIONS: Through-the-scope gastroduodenal stenting tended to be ineffective in patients with poor performance status and long stenosis sites. Stent dysfunction occurred more frequently in patients with poorer performance status. Deployment of 2 stents was a risk factor for perforation. Identification of these risk variables may help yield better gastroduodenal stenting outcomes.

[A case of transcatheter arterial embolization for reduction of a hemorrhagic rectal gastrointestinal stromal tumor].

A 91-year-old woman was referred to our hospital with a primary complaint of hematochezia. A rectal submucosal tumor and an acute hemorrhagic rectal ulcer were noted on colonoscopy. After hemostasis was achieved with APC, the patient was diagnosed with a GIST by EUS-FNA. We performed TAE of the middle and inferior rectal artery to secure hemostasis, because these arteries were also observed to be bleeding during hospitalization. A CT scan and colonoscopy revealed that the rectal GIST had reduced and that the acute rectal ulcer had been successfully treated. We report a case in which TAE was used to achieve tumor reduction of a hemorrhagic rectal GIST.

Cronkhite-Canada syndrome tends to be accompanied by colorectal cancer: Report of seven cases.

Cronkhite-Canada syndrome (CCS) can be difficult to diagnose. To diagnose CCS, it is important to perform endoscopic examination for patients with chronic diarrhea, check for the presence or absence of polyposis, and evaluate inflammation in the mucosa between the polyps. This study reported seven cases of CCS. The age of the patients, which included four men and three women, ranged 48-72 years, and all patients were Asian. The most common symptom among these patients was chronic diarrhea. Three of the patients had rectal cancer. In two patients, the lesions were detected at an early stage and resected via endoscopic treatment. CCS is associated with a high risk of malignant gastrointestinal lesions, especially rectal cancers, and periodic surveillance endoscopy and careful observation are required.

Clinicopathological Features of Methotrexate-associated Lymphoproliferative Disorders in the Gastrointestinal Tract.

Methotrexate may cause methotrexate-associated lymphoproliferative disorder (MTX-LPD); however, this disease is uncommon in the gastrointestinal tract. We examined six patients with MTX-LPD in the gastrointestinal tract at our hospital. All of the lesions were ulcerative. Four cases regressed spontaneously, all of which were positive for Epstein-Barr virus-encoded small RNA by in situ hybridization. Two patients who did not regress were negative for Epstein-Barr virus RNA, one of whom received chemotherapy, and one underwent surgery. The prognosis of this disease is considered to be good. MTX-LPD should considered when ulcerative lesions are observed during endoscopy in patients receiving MTX.

Stage at diagnosis of colorectal cancer through diagnostic route: Who should be screened?

BACKGROUND: Colorectal cancer (CRC) is a global health concern, with advanced-stage diagnoses contributing to poor prognoses. The efficacy of CRC screening has been well-established; nevertheless, a significant proportion of patients remain unscreened, with > 70% of cases diagnosed outside screening. Although identifying specific subgroups for whom CRC screening should be particularly recommended is crucial owing to limited resources, the association between the diagnostic routes and identification of these subgroups has been less appreciated. In the Japanese cancer registry, the diagnostic routes for groups discovered outside of screening are primarily categorized into those with comorbidities found during hospital visits and those with CRC-related symptoms. AIM: To clarify the stage at CRC diagnosis based on diagnostic routes. METHODS: We conducted a retrospective observational study using a cancer registry of patients with CRC between January 2016 and December 2019 at two hospitals. The diagnostic routes were primarily classified into three groups: Cancer screening, follow-up, and symptomatic. The early-stage was defined as Stages 0 or I. Multivariate and univariate logistic regressions were exploited to determine the odds of early-stage diagnosis in the symptomatic and cancer screening groups, referencing the follow-up group. The adjusted covariates were age, sex, and tumor location. RESULTS: Of the 2083 patients, 715 (34.4%), 1064 (51.1%), and 304 (14.6%) belonged to the follow-up, symptomatic, and cancer screening groups, respectively. Among the 2083 patients, CRCs diagnosed at an early stage were 57.3% (410 of 715), 23.9% (254 of 1064), and 59.5% (181 of 304) in the follow-up, symptomatic, and cancer screening groups, respectively. The symptomatic group exhibited a lower likelihood of early-stage diagnosis than the follow-up group [P < 0.001, adjusted odds ratio (aOR), 0.23; 95% confidence interval (95%CI): 0.19-0.29]. The likelihood of diagnosis at an early stage was similar between the follow-up and cancer screening groups (P = 0.493, aOR for early-stage diagnosis in the cancer screening group vs follow-up group = 1.11; 95%CI = 0.82-1.49). CONCLUSION: CRCs detected during hospital visits for comorbidities were diagnosed earlier, similar to cancer screening. CRC screening should be recommended, particularly for patients without periodical hospital visits for comorbidities.

Covered self-expandable metal stents with an anti-migration system improve patency duration without increased complications compared with uncovered stents for distal biliary obstruction caused by pancreatic carcinoma: a randomized multicenter trial.

OBJECTIVES: The requirements of biliary stents used in the palliation of malignant biliary obstruction are a long duration of patency and minimal adverse effects. Covered self-expandable metal stents (SEMSs) have been shown to prevent tumor ingrowth, which is the most frequent complication of uncovered SEMSs. However, because they are prone to migration, the superiority of covered SEMS has yet to be convincingly demonstrated. The aim of this study was to evaluate the superiority of covered over uncovered SEMSs in the palliation of distal biliary obstruction due to unresectable pancreatic carcinoma, using both stent types with relatively low axial force and uncovered flared ends to prevent their migration. METHODS: From April 2009 to December 2010, 120 patients who were admitted to 22 tertiary-care centers because of distal biliary obstruction from unresectable pancreatic carcinomas were enrolled in this prospective randomized multicenter study. Patients were randomly assigned to receive a covered or uncovered SEMS deployed at the site of the biliary stricture during endoscopic retrograde cholangiopancreatography. Stent patency time, patient survival time, patient survival time without stent dysfunction (time to stent dysfunction or patient death), cause of stent dysfunction (ingrowth, overgrowth, migration, or sludge formation), and serious adverse events were compared between covered and uncovered SEMS groups. RESULTS: Patient survival time in the two groups did not significantly differ (median: 285 and 223 days, respectively; P=0.68). Patient survival time without stent dysfunction was significantly longer in the covered than in the uncovered SEMS group (median: 187 vs. 132 days; P=0.043). Stent patency was also significantly longer in the covered than in the uncovered SEMS group (mean±s.d.: 219.3±159.1 vs. 166.9±124.9 days; P=0.047). Reintervention for stent dysfunction was performed in 14 of 60 patients with covered SEMSs (23%) and in 22 of 60 patients with uncovered SEMSs (37%; P=0.08). Stent dysfunction was caused by tumor ingrowth, tumor overgrowth, and sludge formation in 0 (0%), 3 (5%), and 11 (18%) patients in the covered SEMSs group, and in 15 (25%), 2 (3%), and 6 (10%) patients in the uncovered SEMSs group, respectively. Stent migration was not observed in either group. Rates of tumor overgrowth and sludge formation did not significantly differ between the two groups, whereas the rate of tumor ingrowth was significantly lower in the covered than in the uncovered SEMS group (P<0.01). Acute pancreatitis occurred in only one patient in the covered SEMS group. Acute cholecystitis occurred in one patient in the covered SEMS group and in two patients in the uncovered SEMS group. There was no significant difference between the two groups in the incidence of serious adverse events. CONCLUSIONS: By preventing tumor ingrowth and migration, covered SEMSs with an anti-migration system had a longer duration of patency than uncovered SEMSs, which recommends their use in the palliative treatment of patients with biliary obstruction due to pancreatic carcinomas.