A comprehensive global analysis has found that while overall gastric cancer rates are declining in most countries, concerning trends are emerging among adults younger than 50 years, particularly in certain regions. The study examined data from 185 countries using the GLOBOCAN 2022 database and cancer registry information spanning 2003-2017.

The researchers identified an estimated 968,000 new gastric cancer cases and 660,000 deaths globally in 2022. East Asia bore the heaviest burden, accounting for 53.8% of cases and 48.2% of deaths worldwide. The age-standardized incidence rates showed marked geographic variation, ranging from 3.4 cases per 100,000 people in South Africa to 16.1 in East Asia.

"Several countries in Europe, Oceania, and America suggest an increasingly concerning trend among younger individuals, especially females," the researchers reported in Cancer Biology and Medicine. Notable examples included Australia, Colombia, and Ireland, which showed increased incidence rates in both males and females under 50 years between 2003-2017.

The study found significant gender disparities, with males having consistently higher incidence and mortality rates across all geographic regions. The male-to-female ratio ranged from 1.13 in Mid-Africa to 2.38 in East Asia for incidence rates.

Mongolia reported the highest overall rates for both incidence (35.5 per 100,000) and mortality (31.6 per 100,000). The researchers attributed this partly to Mongolia's notably high prevalence of Helicobacter pylori infection, ranging from 67%-76% among individuals with gastric complaints or early-stage cancer.

The analysis also revealed a correlation between gastric cancer burden and human development index levels, though the relationship was described as "weak" (ρ = 0.27, P < 0.001). Countries in transition accounted for approximately 14% of all cases and 18% of all deaths worldwide in 2022.

Obesity and lifestyle factors were noted as contributors to the rising gastric cancer rates in younger populations, particularly in countries with a Western diet. The study highlighted that higher obesity rates among females and populations adhering to Western dietary patterns might increase the risk of cardia gastric cancer in younger individuals. Additionally, the researchers suggested that changes in the gastric microbiome associated with modern lifestyles could play a role.

The researchers noted that while prevention efforts and improved treatments have contributed to declining rates in many countries, "comprehensive prevention strategies tailored to different age patterns are clearly needed" to address the rising trend among younger individuals. These strategies include targeted efforts to address risk factors such as H. pylori infection, obesity, and dietary habits.

The study authors highlighted several limitations, including that GLOBOCAN estimates were based on selected registries (usually in major cities) and might not accurately reflect the overall burden in some countries. Additionally, substantial random variation might occur in countries where analysis was based on small patient numbers.

No potential conflicts of interest were disclosed.