Infection with bacteria that can cause peptic ulcers and distal stomach cancer may be associated with a reduced risk of a type of esophageal cancer called adenocarcinoma, according to a study in the March 3 issue of the Journal of the National Cancer Institute. However, that same study found that people infected with the bacteria, called Helicobacter pylori, who also had gastric atrophy, or "wasting" of the mucous membrane that lines the stomach, were at an increased risk of another type of esophageal cancer called squamous-cell carcinoma.
Earlier studies have suggested that H. pylori infection may be associated with a reduced risk of esophageal adenocarcinoma (cancer that arises in the tissue at the lower part of the esophagus), perhaps because such an infection may induce gastric atrophy, leading to less acidic stomach fluids that are less harmful to esophageal tissue. In contrast, researchers have speculated that H. pylori infection may increase the risk of squamous-cell carcinoma (cancer that arises in the cells that line the esophagus) by stimulating the production of cancer-causing nitrosamines.
To investigate the relationship among H. pylori infection, gastric atrophy, and three types of cancer--esophageal adenocarcinoma, esophageal squamous-cell carcinoma, and gastric cardia adenocarcinoma--Weimin Ye, M.D. Ph.D., of the Karolinska Institute in Stockholm, Sweden, and colleagues looked at H. pylori infection rates and the presence of gastric atrophy among 133 patients with the three types of cancer and compared them with 499 control patients.
They found that H. pylori infection was associated with a 50% to 80% reduction in risk of esophageal adenocarcinoma, depending on the type of analysis used. However, gastric atrophy was not associated with risk of the disease, which suggests, the authors say, that gastric atrophy does not play a role in the proposed protective effect of the infection. For squamous-cell carcinoma, H. pylori infection was associated with a two-fold increased risk of the disease, and the increased risk was even higher among those that had gastric atrophy. This suggests "that gastric atrophy may be an intermediate step in the pathway from … H. pylori infection to squamous-cell carcinoma," the authors write.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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