A new review is suggesting that a type of bacteria, called Helicobacter pylori, which reside in the stomachs of humans may aid in the protection against the development of a type of oesophageal cancer, known as adenocarcinoma.
The review of the medical literature discovered that those having H. pylori strains carrying a gene called CagA were 50 percent more prone to get adenocarcinoma of the oesophagus.
Adenocarcinoma of the oesophagus is a cancer that develops in the tube that passes food from the throat to the stomach.
For the study, Kamangar and co-author Farhad Islami of the University of Tehran in Iran analysed results from 19 published studies examining the associations of H. pylori with oesophageal adenocarcinoma and oesophageal squamous cell carcinoma, another type of oesophageal cancer.
"CagA- positive strains of H. pylori may decrease the risk of adenocarcinoma by reducing acid production in the stomach and, therefore, reducing acid reflux to the esophagus," said study co-author Dr. Farin Kamangar, a research fellow at the National Cancer Institute.
He added: "It may also work by decreasing the production of the hormone ghrelin, which is secreted from the stomach to stimulate appetite. A reduction in the level of ghrelin may lead to lower rates of obesity, an important risk factor for adenocarcinoma."
According to the study, it's the falling rates of H. pylori bacteria in developed populations that causes the increasing rate of occurrence of oesophageal adenocarcinomas.
Kamangar said that despite its potential for causing stomach cancer and ulcers, H. pylori's long history of co-existence with humans suggests it also may have some beneficial effects, including possible roles in reducing diarrhoeal diseases and asthma.
The study is published in the latest issue of Cancer Prevention Research, a journal of the American Association for Cancer Research.