Helicobacter pylori and colorectal cancer—A bacterium going abroad?

Abstract

Helicobacter pylori is a bacterium that infects the mucus gel layer above the gastric epithelium in approximately half of the world’s population [1]. Infection with H. pylori causes gastritis, which may become chronic. Chronic inflammation of the stomach mucosa leads to morphological changes in the gastric epithelium transitioning from chronic atrophic gastritis to intestinal metaplasia, dysplasia, and, in 1%–3% of H. pylori–infected individuals, to gastric cancer [2]. This progression from normal to cancerous tissue takes decades and can be inhibited by eradication of the bacterium through antibiotic treatment [2]. Besides causing gastric cancer, which was officially acknowledged by the World Health Organization in 1994 [3], the presence of H. pylori has been associated with other diseases as well. Within the stomach, H. pylori increases risk of peptic ulcer and lymphoma of mucosa-associated lymphatic tissues; outside of the stomach, H. pylori has been found to be associated with not only a range of noncancerous diseases, including asthma, Parkinson, and diabetes, but also other cancerous outcomes in the gastrointestinal tract, particularly the colorectum [4, 5].