Asunción García
Senior researcher at the Aragon Institute of Health Sciences, the Aragon Health Research Institute, and member of the CIBER in liver and digestive diseases (CIBERehd)
Gastric cancer is a complex pathology that represents a serious global health burden. Despite a decreasing incidence in most industrialized countries, gastric cancer still ranks as the fifth most common cancer and the fifth most frequent cause of cancer deaths worldwide. This neoplasm shows large geographic differences with relatively low rates in most Western countries, including the United States, and high rates in Eastern Asia (Japan, Korea, and China), and certain areas of Central and South America. This variability in gastric cancer incidence is due to complex interactions between environmental and host factors. Among them, Helicobacter pylori infection has been identified as the single most common cause of gastric cancer and, in this context, it was classified in 1994 as a class I carcinogen by the World Health Organization. This organism, which colonizes over half of the world’s population, first induces chronic superficial gastritis in most infected people, initiating a process that in certain individuals may lead to gastric cancer.
This study by Park et al. published in Nature Medicine first quantifies the future burden of gastric cancer among individuals born between 2008 and 2017, assuming no changes in the current practices of gastric cancer prevention. According to the authors, 15.6 million people in 185 countries will be diagnosed with gastric cancer in their lifetime and, interestingly, 76% of those cases may be attributable to Helicobacter pylori infection. This is a comprehensive study based on national age-specific incidence rates reported from GLOBOCAN 2022 and cohort-specific mortality rates reported from the United Nations’ demographic projections. Their results highlight Asia as the main contributor to the estimated burden of gastric cancer (10.6 million cases), followed by the Americas (2.0 million cases) and Africa (1.7 million cases). Of note, much of the global burden of gastric cancer continues to occur in very high- or high-incidence countries in East Asia, mostly in China, due to their large and aging populations. However, projections also suggest that in areas of relatively low incidence, such as Africa, the incidence of gastric cancer could be at least six times higher than 2022 estimates. These Helicobacter pylori-attributable cases are assumed to be potentially preventable through implementing population-based Helicobacter pylori screen-and-treat programs. In this context, Park and co-authors estimate that the implementation of population-level Helicobacter pylori screen-and-treat strategies will reduce the expected number of gastric cancers up to 75%. Nevertheless, there have been few attempts to implement such population programs even in high-risk areas, although several European countries have recently initiated pilot studies as part of Europe’s Beating Cancer Plan.
The authors highlight the fact that gastric cancer will remain a major public health problem globally over the next decades, and call for greater investment in its prevention, mainly through population-wide Helicobacter pylori screen-and-treat programs. However, and despite the well documented link between Helicobacter pylori and gastric cancer, it is still a matter of speculation as to why only a minority (<1%) of individuals infected with the bacteria develops gastric malignancy, suggesting that factors other than bacterial infection alone participate in the carcinogenesis process. In fact, epidemiological studies indicate that approximately 30% of gastric cancers are attributable to other modifiable risk factors such as alcohol consumption, smoking, obesity and insufficient physical activity. In addition, there is accumulating evidence that genetic susceptibility plays a major role in the development of the disease. Therefore, new programs and strategies developed to mitigate the increasing gastric cancer burden should consider all potential risk factors involved in such a complex pathology as gastric cancer.