Composition, diversity and potential utility of intervention-naïve pancreatic cancer intratumoral microbiome signature profiling via endoscopic ultrasound

We read with great interest the recent article by Cheng et al that discussed the topic of gut microbiome modulation, which may promote sensitivity or resistance to chemotherapeutic agents or immune checkpoint inhibitors.1 Historically, the pancreas was considered to be a sterile organ; however, bacterial DNA has been detected in 76% of surgically resected pancreatic ductal adenocarcinoma (PDAC) samples, some of which had prior biliary instrumentation, and in 15% of normal pancreas controls.2 3 It is unknown how bacteria may colonise the pancreas, but some have postulated bacterial reflux into the pancreatic duct via the major/minor papilla as a possibility and by dysbiosis due to pancreatitis, obesity, smoking and diabetes, as it alters gut permeability.4 5 Intratumoral microbiome composition may also impact therapeutic drug sensitivity and disease survival.6 The presence of PDAC intratumoral Gammaproteobacteria has the potential to inactivate gemcitabine sensitivity via the bacterial enzyme cytidine deaminase.7 Conversely, Bifidobacterium is believed to promote beneficial effects on …