The Causal Role of Bile Acids in Cancers of the Digestive System

Bile acids are widely distributed in the human gastrointestinal tract. A literature review indicates a role for bile acids in initiating cancers in every organ of the digestive system. The estimated number of new digestive system cancers world-wide in 2022 was about 5 million. For esophageal adenocarcinoma, stomach cancer and small intestine cancer, bile reflux plays a significant role in carcinogenesis. For colon cancer, secondary bile acids produced in response to a high fat diet disrupt colonic epithelial cell mitochondrial membranes. This disruption leads to release of oxidative free radicals that damage DNA and can cause carcinogenic mutations. Cancers of the pancreas, liver, and biliary tract can be caused by constriction of the common bile duct leading to reflux of bile acids back into these organs. Gastroesophageal reflux involving bile acids may also contribute to hypopharyngeal squamous cell carcinogenesis. Thus, bile acids are a likely major contributory cause of cancer throughout the digestive tract.