Eliminating common bacterial infection significantly decreases gastric cancer risk

November 13, 2019

PHILADELPHIA - While it is well known within the medical community that there is a link between the bacteria Helicobacter pylori (H. pylori) and rates of gastric cancer--commonly referred to as stomach cancer--the rates and risk among Americans has been largely understudied. Now, after analyzing records of close to 400,000 patients, researchers in the Perelman School of Medicine at the University of Pennsylvania, have found that successfully eliminating H. pylori from one's gastrointestinal tract led to a 75 percent reduction in risk of gastric cancer. Researchers also found that rates of gastric cancer after detection of H. pylori infection are higher among specific populations, suggesting that people who fall into these groups could benefit from more careful monitoring. The study is published in the journal Gastroenterology.

H. pylori is estimated to infect half of the world's population, largely those in the eastern parts of the world. It can cause ulcers and other gastrointestinal issues but does not cause issues in the majority of people, and so many people are unaware they have it.

"The problem was that all research out of the U.S. used to study gastric cancer and determine American's risk of developing it did not take into account H. pylori infection, and studies worldwide have shown this infection is actually the leading risk factor for this type of cancer," said the study's lead author Shria Kumar, MD, a fellow in the division of Gastroenterology.

The research team found that African American, Asian, Hispanic and Latinx, American Indian and Inuit Americans have significantly higher risk of H. pylori infection and of developing gastric cancer. Risks, when compared to the general population, are also higher among men, those who smoke, and among those whose H. pylori infection is detected in older age.

"Discovering that these particular racial and ethnic groups are more likely to develop cancer after detection of this bacteria could influence clinicians' future screening practices and hopefully lead to early detection and management of gastric cancer," said Kumar.

Kumar and the research team also saw that eradication of H. pylori infection dropped gastric cancer risk by about 75 percent, but that simply prescribing the H. pylori regimen does not decrease the likelihood of getting this cancer. Authors noted that this finding suggests physicians should ensure that the bacteria is eradicated after treatment, a consensus guideline recommendation that is often not followed due to the cumbersome nature of H. pylori testing.

While H. pylori and gastric cancer have serious consequences, Kumar is optimistic that the information from this study can lead to further research on the merits of increasing screening. Screening for H. pylori requires an endoscopic procedure, breath test, or stool sample, so it's necessarily not easy. In addition, even among the number of people in the United States who contract H. pylori, most do not develop gastric cancer.

"According to estimates, there will be 27,000 new cases of gastric cancer in the U.S. this year, which is small compared to the prevalence of colorectal cancer - for which there is an estimated 101,000 new cases for 2019," said Kumar. "It's not feasible or necessary to screen everyone for H. pylori or gastric cancer, but our study suggests that certain people may have high enough compounding risk to warrant regular invasive screenings and anyone treated for an H. pylori infection should be assessed to ensure eradication of the bacteria."
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Additional authors include Penn's David C. Metz, Susan Ellenberg, and David E. Kaplan. The study's senior author is David S. Goldberg, who is now with the University of Miami, Miller School of Medicine. Shria Kumar is supported by an NIH training grant (5 T32 DK 7740-22).

Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $7.8 billion enterprise.

The Perelman School of Medicine has been ranked among the top medical schools in the United States for more than 20 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $425 million awarded in the 2018 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: the Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center--which are recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report--Chester County Hospital; Lancaster General Health; Penn Medicine Princeton Health; and Pennsylvania Hospital, the nation's first hospital, founded in 1751. Additional facilities and enterprises include Good Shepherd Penn Partners, Penn Home Care and Hospice Services, Lancaster Behavioral Health Hospital, and Princeton House Behavioral Health, among others.

Penn Medicine is powered by a talented and dedicated workforce of more than 40,000 people. The organization also has alliances with top community health systems across both Southeastern Pennsylvania and Southern New Jersey, creating more options for patients no matter where they live.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2018, Penn Medicine provided more than $525 million to benefit our community.

University of Pennsylvania School of Medicine

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