Review: Prevention and management of gastric cancer

Gastric cancer (GC) is still the fifth most frequently diagnosed cancer and the third leading cause of cancer deaths in both sexes worldwide. Although the incidence of GC is predicted to continue declining in a growing number of countries in the future, on a global scale the number of newly diagnosed GC cases will remain high, or increase even further, due to changes in population size and increasing risks observed in younger generations. In a retrospective cohort study, collecting data from the Veterans Health Administration, treatment of Helicobacter pylori infection decreased GC risk only if eradication was successful. In a German case‐control study, among GC patients with autoimmune gastritis, pernicious anemia was associated with earlier detection of GC, which translated into a significantly better 5‐year survival. In an updated meta‐analysis, H. pylori eradication therapy in healthy individuals significantly reduced both GC incidence and mortality from GC with a number needed to treat of 72 and 135, respectively. In Korea, successful H. pylori eradication substantially reduced GC incidence in first‐degree relatives of GC patients as well. A meta‐analysis of four trials including 1,556 patients with resectable GC reported that the patient subgroup tumors with high microsatellite instability undergoing surgery did not benefit from perioperative or adjuvant chemotherapy.

GC still ranks as the fifth most frequently diagnosed cancer and is the third leading cause of cancer death in both sexes worldwide.
However, GC incidence is steadily decreasing globally, and in some populations is now regarded as a rare disease.
In a registry-based study, Arnold et al extracted data on GC incidence by year of diagnosis, sex, and age from 92 cancer registries in 34 countries, based on the International Classification of Diseases, 10th revision: C16. 1 The numbers of new cases and age-standardized incidence rates per 10,000 by country, sex, and age, beginning in 2012, were extrapolated to 2035 and fitted to recent trends using a log-linear age-period-cohort model that levels off exponential growth and limits linear trend projection. According to their analysis, overall GC incidence rates will fall further in both high-and low-incidence countries (ie, Japan and Australia, respectively). They also predict that, by 2035, GC incidence rates will fall below the rare disease threshold (defined as 6 per 100 000 person-years) in 16 out of the 34 evaluated countries. In contrast, alarming incidence increases will be observed in younger age groups (below 50 years of age) in both low-incidence and high-incidence populations. On a global scale, they predicted that the number of newly diagnosed cases will remain high or increase even further. Changes in the population size and structure, as well as in the prevalence of risk factors, especially in those aged below 50 years, are likely to explain this development.
Thus, while in some regions GC will become a rare disease, in others it will remain a major public health challenge. International Classification of Diseases (ICD), Revision 9/10 codes. For patients with multiple criteria, the criterion with the earliest date was used. Patients with non-cardia GC were identified using the Veterans Affairs Central Cancer Registry and/or ICD 9/10 codes.
With respect to non-cardia GC, the cumulative incidence of cancer was 0.37% at 5 years and increased to 0.5% and 0.65% after 10 and 20 years post-detection of H. pylori infection, respectively.
Older age and a history of smoking both slightly increased the cancer risk, with a sub-hazard ratio [

| TRE ATMENT
Mismatch repair deficiency (dMMR)-/microsatellite instability (MSI)high status is gaining attention for its possible role as a prognostic and possibly predictive biomarker in patients with GC. However, GCs with dMMR-/MSI-high status represent only 9% to 22% of all diagnosed GC cases, and thus large data sets are needed to draw robust evidence concerning its prognostic/predictive value.
In an individual patient data meta-analysis of four prospective

| CON CLUS IONS
Although in the near future GC incidence rates will fall below the rare disease threshold in many countries, on a global scale the number of newly diagnosed GC cases will remain high, or increase even further, due to changes in population size and increasing risks observed in younger generations. Successful eradication of H. pylori is the key to GC prevention. Accumulating evidence suggests that, in patients with MSI-high resectable GC, chemotherapy may be omitted. Precision oncology has become the standard of care for a selected group of patients, but no advances were made in systemic therapy for the majority of patients with advanced GC during the last year, and thus, more efforts in this field are warranted.