Researchers calculate the future incidence of gastric cancer in children and adolescents today

In general, the article does not say anything new. It provides a general analysis of the incidence of gastric cancer worldwide among men and women and by age, and states that it is the fifth most common cancer. These data are already well known.

The incidence of gastric cancer has two very important conditions. One is Helicobacter pylori. As the article states, three-quarters of gastric cancers are directly related to Helicobacter pylori, although the figure is probably higher, and this is already known.

The other important factor is all dietary conditions and genetic predisposition.

Therefore, Helicobacter pylori plays a fundamental role and runs parallel to the prevalence of the infection worldwide, such that underdeveloped countries have, on the one hand, poorer hygiene and sanitation conditions and higher prevalence rates of Helicobacter pylori, above 50-60%. In contrast, in Western countries such as Spain and others, the prevalence of Helicobacter pylori has fallen dramatically and is now below 35%.

Is prevention necessary? It will depend on the geographical area, fundamentally, and also on the prevalence of Helicobacter pylori infection and the incidence of gastric cancer in different regions. Therefore, it is not possible to give general advice on gastric cancer.

In Spain, the number of cases of gastric cancer has been steadily declining, as have the rates of infection with Helicobacter pylori. In Spain, it ranks eleventh in terms of incidence, so strategies to screen for and treat Helicobacter pylori are probably not cost-effective here. They may be in other countries or with other prevention campaigns, such as those carried out in Japan, with screening through gastroscopy or other techniques.

Therefore, the article as a whole adds little to what is already known and I believe it falls short of expectations regarding Helicobacter pylori or the prevention of gastric cancer. An important role has been played by the vaccine against Helicobacter pylori, which has been discussed for decades but, to date, there is nothing effective to eradicate or prevent this infection. The other treatments have advantages and disadvantages in terms of techniques and diagnostics applicable to the general population, acceptance, and the effects that eradication treatments may have.

As for the incidence of gastric cancer in young people, it is relatively low, probably less than 6%, which is very alarming, but in real terms it is being taken out of context and each cancer should be analysed individually.

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. 

The study by Park and colleagues poses major challenges for the clinical and scientific community worldwide. The study makes a projection of the estimated number of new cases of stomach cancer diagnosed in the coming years, considering in particular the world population born between 2008 and 2017, and how many of these cases could be attributed to infection with the bacterium Helicobacter pylori. These numbers are dramatic, indicating that of the 1.347 billion people born, at least 15.6 million will suffer from gastric cancer and 75.8% will be attributable to this bacterium.

It should be noted that Helicobacter pylori is a bacterium that has been declared a type I carcinogen by the International Agency for Research on Cancer (IARC), meaning that there is sufficient scientific evidence to say that this bacterium can cause cancer. Unfortunately, the bacterium is highly prevalent and could be infecting more than 50% of the population in general. This bacterium promotes the development of gastritis and, if the infection persists without treatment, it promotes more serious stomach lesions over time, such as cancer.

For this reason, the work of Park and colleagues is a warning and highlights, with solid data, that countries with high human development indices will account for 50% of these cases of gastric cancer, suggesting that research and screening strategies to prevent this type of tumour may not be sufficient. The authors emphasise existing global disparities, highlighting initiatives such as EUROHELICAN and TOGAS in the European Union and the actions of South Korea, Japan and China, which have focused on national and regional digestive endoscopy programmes, and contrasting these with the lack of active programmes in regions of the Americas and Africa, reinforcing the urgent need for policies and greater efforts, not only for the prevention of gastric cancer, but also for the eradication of Helicobacter pylori. It should be noted that this bacterium has shown resistance to conventional antimicrobial therapies commonly used for its elimination. Therefore, diagnostic and therapeutic tools also pose a challenge in terms of access for different communities and human groups, depending on their own public health policies and economic capacity.

In their discussion, the authors invite authorities and the scientific community to take a different view of this situation: gastric cancer would no longer be a problem only in countries commonly associated with high incidence of this disease, but rather a generational problem, since an individual during their lifetime may be exposed to Helicobacter pylori infection on multiple occasions or live with this infection for many years before having access to timely diagnosis and treatment. In turn, eradication of the bacterium would be decisive for a sustained reduction in the risk of developing stomach cancer.