Biliary stents can modify the microbiota and promote the progression of pancreatic cancer.

Pancreatic cancer (PC), the fourth cause of cancer-related deaths, is an aggressive disease with an increased worldwide incidence. Pancreatic ductal adenocarcinoma (PDAC), ~90% of pancreatic malignancies, arises from pancreatic ducts. PC has a unique microenvironment hosting a heterogenous combination of cell populations, including immune cells and microbes. Microorganisms appear involved in every step of PC's natural history, from creating a predisposing environment for in situ carcinogenesis to cell migration and metastasis. Biliary stent placement through endoscopic retrograde cholangiopancreatography (ERCP) can mitigate jaundice in PC patients but may alter the intestinal microbiota and contribute to tumor initiation and progression. Disruption of the antimicrobial barrier of the sphincter of Oddi, due to endoscopic sphincterotomy and stent insertion, promotes duodenal reflux, permitting bacterial colonization and biofilm formation. Although ERCP is the preferred drainage route, studies reported lower complication rate and reduced dysbiosis with percutaneous transhepatic biliary drainage (PTBD). The biliary microbiome in stented patients undergoing pancreaticoduodenectomy is altered, exhibiting higher levels of Enterococci, Klebsiella, and Candida species. The decision to place a biliary stent in PC patients should be carefully considered, given the potential for dysbiosis and its impact on therapeutic resistance. This underscores the need for further research into interventions that could modulate the microbiota, such as PTBD, probiotics or targeted microbial therapies.