Background/Aim: Several types of adverse events are caused by endoscopic placement of self-expandable metal stents for malignant distal biliary obstruction (MDBO) caused by pancreatic cancer (MDBO). The aim of our study was to investigate early adverse events and recurrent biliary obstruction in patients who undergo endoscopic placement of SEMSs for MDBO caused by pancreatic cancer.
Methods: The study conducted a retrospective analysis of the incidence and variety of adverse events in patients who underwent SEMS placement for MDBO from April 2018 to March 2021 in 26 hospitals. The study retrospectively analyzed clinical data of all consecutive patients who underwent SEMS placement for MDBO from April 2018 to March 2021 at 26 hospitals. Each risk factor for adverse events was evaluated by univariate and multivariate analyses. The study evaluated risk factors for conditions such as acute pancreatitis, cholecystitis, and an RBO by using both univariate and multivariate analysis.
Results: Of 1113 patients, 175 patients (15.7%) observed early adverse events. Among early adverse events, acute pancreatitis and cholecystitis were observed in 69 patients (6.2%) and 51 patients (4.6%), respectively. Female (p=0.029), pancreatic duct without tumor involvement (p = 0.002), and intact papilla ( p = 0.044) were independent risk factors for acute pancreatitis. Tumor involvement in the orifice of the cystic duct (OCD) ( p < 0.001), endoscopic sphincterotomy (p = 0.028), and endoscopic pancreatic sphincterotomy (p = 0.048) an independent risk factor for cholecystitis.
RBO throughout the entire study period was observed in 294 cases (26.4%). RBO was caused by food impaction and/or sludge formation , stent migration, tumor overgrowth, and tumor ingrowth in 11.0%, 8.6%, 2.4%, 2.3% of patients, resepcetively. The duodenal invasion ( p=0.024) was an independent risk factor for RBO. Fully covered SEMS (FCSEMS)(p=0.032), Partially covered SEMS(PCSEMS) (p= 0.021), and diameter of SEMS (<10 mm) (p=0.033) were independent risk factors for food impaction and/or sludge formation. FCSEMS (p=0.028), low BMI (<20.4) (p=0.030), and administration of chemotherapy (p=0.018) were independent risk factors for stent migration. The duodenal invasion (p=0.005) was an independent risk factor for tumor overgrowth. Uncovered SEMS (p <0.0001 vs. FCSEMS, p = 0.004 vs. PCSEMS), and laser-cut SEMS (p = 0.072) were independent risk factors for tumor ingrowth.
Conclusions: Significant risk factors were female, pancreatic duct without tumor involvement, and an intact papilla for pancreatitis, and tumor involvement to the OCD, endoscopic sphincterotomy, and endoscopic pancreatic sphincterotomy for cholecystitis. The risk factors for food impaction and/or sludge, stent migration, and tumor ingrowth differed by diameter of structure, and types of SEMS.

Osamu Inatomi

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