Detection of Helicobacter pylori in extragastric tissues: association of infection with carcinogenesis

Introduction: Helicobacter pylori (HP) is a gram-negative microaerophilic bacterium that has been described as the main pathogen of several benign and malignant diseases of the digestive tract, such as gastric and duodenal ulcers, chronic gastritis, hepatobiliary diseases, gastric lymphoma, and carcinoma. HP was classified as class I human carcinogen in 1994. The relationship between HP infection and extragastric diseases has been investigated over the years with contradictory conclusions. The objective of this work is to perform a bibliographic review on the association between HP infection and the development of extragastric pathologies, particularly of pancreatic carcinoma. It is also intended to determine the best method for the detection of the bacterium. Materials and methods: work was based on the literature from the following databases: b-on, PubMed, SciELO, Wiley Online Library and Scientific Repository of the Polytechnic Institute of Lisbon, under the terms “Helicobacter spp.”, “Helicobacter pylori”, “pancreatic cancer”, “extragastric diseases”, “risk of pancreatic cancer” and “CagA”. From a total of 32 analyzed articles, 18 were selected, excluding those with dubious methods and results that were not performed in human samples and meta-analysis. Results: In the selected studies the presence of HP DNA was detected by Polymerase Chain Reaction (PCR) in more than 50% of the pancreatic and hepatocellular cancer samples. There was also an association between the presence of this bacterium and colonic cancer, primary sclerosing cholangitis, primary biliary cirrhosis, cholecystitis and biliary tract carcinoma. However, detection by enzyme-linked immunosorbent assay provided ambiguous results, with 2 of the studies showing no association between infection and pancreatic cancer, while others showed positive results below 50%. There are also 3 studies that related the seroconversion of cytotoxin-associated gene A negative to pancreatic carcinoma. Other methods like histochemical and immunocytochemistry (ICQ) ...