ANN ARBOR— Researchers at the University of Michigan have completed a study that provides compelling clinical and economic evidence for population-based Helicobactor pylori (H pylori) screening to reduce the risk of gastric cancer.

Investigators, employing a comprehensive computer analysis, found that H pylori screening could potentially provide important health benefits at a reasonable cost even if elimination of H pylori reduced the increased risk of gastric cancer by only 15 percent in infected individuals.

The study is published in Archives of Internal Medicine.

H pylori’s role in most peptic ulcer disease cases has been well documented. People infected with H pylori are also at an increased risk for gastric cancer, prompting the World Health Organization to classify H pylori as a group 1 carcinogen in humans. However, to date, no clinical trial has demonstrated whether the elimination of H pylori infection actually decreases an infected person’s already-increased risk for this relatively rare, but frequently lethal, cancer.

“A clinical trial providing definitive evidence that elimination of H pylori infection reduces gastric cancer risk will not be completed for several years,” says A. Mark Fendrick associate professor of internal medicine in the U-M Health System. “In the interim, we constructed a computer simulation to estimate the potential health and economic consequences of H pylori screening over a range of cancer risk-reduction.

“The ease and low cost of H pylori diagnosis and treatment should make screening attractive to both patients and health care providers. Interestingly, if elimination of H pylori infection reduces cancer risk significantly, this cancer prevention program has the potential to be more cost-effective than mammography and PSA testing.”

This is largely due to two factors. First, gastric cancer strikes earlier in life than other common cancers. Therefore, each gastric cancer case prevented led to a significant number of life-years saved. Second, a person only has to be screened for H pylori once in their lifetime since H pylori infection is usually acquired in childhood and re-infection is extremely rare in adults.

The computer model determined that one-time H pylori screening was cost-effective when H pylori eradication reduced the risk of gastric cancer in infected individuals by as little as 15 percent. The analytical model also estimated that H pylori treatment guided by a simple blood test provided a relatively low cost per life-year saved. If elimination of H pylori lowered the risk of gastric cancer to a level similar to individuals who were never infected, just over $6,000 would need to be spent on screening to save an additional year of life—a dollar amount far lower than many commonly accepted medical interventions.

“We set out to estimate the level of cancer risk-reduction necessary to make it worthwhile to recommend H pylori screening to individuals at low risk of gastric cancer on both clinical and economical grounds,” Fendrick says. “Since many Americans have a great fear of cancer, we believed they would undergo a simple blood test and take medications for two weeks to reduce the risk of a rare but highly fatal cancer, even if the definitive evidence was not in.”

Fendrick says a parallel could be drawn to prostate-specific antigen testing (PSA) to detect prostate cancer. “Even though there remains uncertainty whether detecting early prostate cancers saves lives, Americans have adopted this strategy with unbridled enthusiasm. This decision is based not entirely on the scientific evidence. I would venture to say that the adoption of this or any unproven cancer screening program is driven by our cancer phobia.”

H Pylori is usually treated with a two-week regimen consisting of a combination of two antibiotics and a medication that decreases acid product in the stomach. This treatment plan is successful more than 90 percent of the time in permanently eliminating H pylori infection.

“Population based screening of asymptomatic individuals has the potential to produce real important health benefits in terms of reducing gastric cancer,” Fendrick says, “because each gastric cancer case prevented led to a significant number of life-years saved.”

The study was conducted by researchers in the Consortium for Health Outcomes, Innovation and Cost-Effectiveness Studies (CHOICES)—a research unit funded jointly by the Departments of Medicine and Surgery devoted to the Multidisciplinary study of the quality and economic impact of health care services.