Common microorganism causes millions of cases of gastric cancer

The Independent

La Jornada Newspaper, Thursday, July 10, 2025, p. 6

A common bacteria is behind millions of cases of stomach cancer worldwide, although early screening could be key to reducing its impact, experts warn.

Researchers at the World Health Organization's (WHO) International Agency for Research on Cancer (IARC) project that, if current trends continue, approximately 15.6 million people born between 2008 and 2017 will be diagnosed with stomach cancer in their lifetime.

Of those cases, about 11.9 million, or 76 percent, are believed to be related to infection by Helicobacter pylori , a bacterium that infects the stomach lining and is one of the most common in the world's population.

While most new cases of gastric cancer are expected to be concentrated in Asia, especially India and China, estimates indicate that the Americas could account for nearly 2 million cases; Africa, 1.7 million; and Europe, around 1.2 million.

Contaminated food and water

Helicobacter pylori ( H. pylori) is a bacterium that infects the stomach lining and is believed to be transmitted both from person to person and through contaminated food and water. Although the precise nature of its spread and how it contributes to the development of cancer is still being studied, it has already been linked to cases of stomach cancer and non-Hodgkin lymphoma. In many people, the infection is asymptomatic and does not require treatment. However, in others, it can cause persistent symptoms such as indigestion, nausea, or bloating.

The infection can be diagnosed through blood tests, breath tests, or stool studies.

The authors of the most recent study call for increased investment in stomach cancer prevention, particularly through mass H. pylori screening and treatment programs in the general population. However, according to data from Cancer Research UK, gastric cancer rates have declined in the United Kingdom: they fell by 26 percent in the last decade and are expected to continue to decline until 2040.

Rachel Orritt, head of health information at the organization, explained that “ Helicobacter pylori infection increases the risk of stomach cancer, but it is not common in the United Kingdom. Stomach cancer cases have been declining for decades and are expected to continue to do so. Although it represents a significant problem worldwide, in the United Kingdom, other predictable factors are driving more cases. Among the recommendations for reducing the risk of developing cancer, she highlighted: quitting smoking, maintaining a healthy weight, moderating alcohol consumption, and adopting a healthy diet.”

For a study in Nature Medicine , scientists examined the global incidence of stomach cancer in 185 countries through 2022 and combined it with projections of future mortality.

Researchers evaluated the potential impact of implementing Helicobacter pylori screening and treatment programs and concluded that these could reduce stomach cancer cases by up to 75 percent.

According to the data, Asia accounts for the majority of projected cases, with 10.6 million (68 percent of the total), followed by the Americas with 2 million (13 percent); Africa with 1.7 million (11 percent); Europe with 1.2 million (8 percent); and Oceania with 70,000 (0.4 percent).

Jin Young Park, head of the IARC stomach cancer prevention team and co-author of the report, stressed that “it is crucial that health authorities prioritize stomach cancer prevention and advance pilot schemes and feasibility studies that include H. pylori screening and treatment programs.”

Among the most common symptoms of this cancer are heartburn or acid reflux, difficulty swallowing, feeling sick, indigestion, frequent belching, and a feeling of rapid satiety when eating.