Helicobacter pylori: Friend or foe?

August 2000

WASHINGTON, D.C. - Although Helicobacter pylori increases the risk for ulcer disease and gastric cancer, its presence may decrease the risk of esophageal diseases including adenocarcinoma, according to Martin J. Blaser, MD.

"Having H. pylori is a trade-off. If you have it, it's bad for your lower stomach. If you don't have it, it's bad for your esophagus," Blaser said at a press conference here sponsored by the National Foundation for Infectious Diseases.

Gastric cancer was the leading cause of cancer deaths in the West, explained Blaser, who is chairman of the department of medicine at New York University School of Medicine, New York City. "But it has been declining over the course of the 20th century. And we now know that that decline is in part due to the disappearance of H. pylori." said Blaser, who is also the Frederick H. King Professor of internal medicine and professor of microbiology at NYU.

Increasing cancer rates

Although squamous cancer of the esophagus also has been declining, adenocarcinoma of the esophagus has been increasing dramatically. "It is the fastest increasing cancer in the United States. It is increasing at a rate of 11% a year, compounded annually," Blaser said. The rate of increase is even higher in other parts of the world.

These cancers begin with gastroesophageal reflux disease (GERD), which can lead to Barrett's syndrome (peptic ulcer of the lower esophagus), dysplasia, and eventually, to esophageal and gastric cardia adenocarcinomas. "There appears to be a reciprocal relationship between these gastric diseases and esophageal disease," he explained.

When people acquire Helicobacter they develop gastritis, a cellular response in the mucosa, and this increases the risk of ulcer disease and stomach cancer. However, these same factors appear to be protective against esophageal diseases, according to Blaser.

The most important risk factor of adenocarcinoma of the esophagus appears to be reflux, which is a higher risk factor than obesity, smoking or other tobacco use.

"Over the past four years, a body of evidence has been growing that indicates that the disappearance of H. pylori is related to the rise of these diseases," he explained. People who do not have H. pylori present, especially one subtype, the cagA+ variety, have higher rates of GERD, Barrett's syndrome and esophageal adenocarcinoma.

Gastric physiology

Gastric colonization by H. pylori appears to affect gastric physiology in a way that diminishes acid production. The decreased colonization is "the first example of a larger issue, that changes in our indigenous bacterial flora have been occurring over the last century, and that these changes may have clinical consequences," Blaser said.

H. pylori colonization has been decreasing in the 20th century, and this is due to many factors. "One factor that is particularly interesting to me is that some recent evidence suggests that the major amplifier of H. pylori is children. Most children get H. pylori from other children, and it turns out that there are fewer children around than there used to be. Family size has decreased, and so transmission of a number of different microbes has decreased. The average age at which children are getting some of these microbes has gone up, or they're not getting it all," Blaser said.

Transmission is also slowing because of cleaner water and improvements in hygiene.

And finally, antibiotic use has played a factor. "We know from other trials that even single courses of antibiotics, for other reasons, can cause H. pylori to go away," Blaser said, "and the average child in the United States gets six courses of antibiotics by the age of 15 just for otitis media."

Antibiotics for ulcers

Another consideration is the use of antibiotics to treat ulcers, although Blaser said this strategy is appropriate if the diagnosis is correct. "Most patients who come to their doctor with abdominal pain do not have an ulcer. They have something we call non-ulcer dyspepsia, or NUD." Eradicating H. pylori has no effect on NUD, he said.

"And the point that is interesting to me is that we could take people who have those symptoms, and we could, by getting rid of H. pylori, be giving them new esophageal symptoms, or putting them at risk for esophageal disease 20 to 30 years later. I think we're at the early point of an epidemic of esophageal adenocarcinoma."

For more information:

• Blaser MJ. In a world of black and white, Helicobacter pylori is gray. Ann Intern Med. 1999;130:695-697.
• Blaser MJ. The changing relationships of Helicobacter pylori and humans: implications for health and disease. J Infect Dis. 1999;179:1523-1530.