Incidence, Risk Factors, and Temporal Trends of Small Intestinal Cancer: A Global Analysis of Cancer Registries.

BACKGROUND & AIMS: Small intestinal cancer is a rare cancer, with limited studies exploring its epidemiology. To our knowledge, this study is the first effort to comprehensively analyze the incidence, risk factors, and trends for small intestinal cancer by sex, age, and country. METHODS: Global Cancer Observatory, Cancer Incidence in Five Continents Plus, and Global Burden of Disease were accessed to estimate the age-standardized rates of small intestinal cancer incidence (International Classification of Diseases, 10th Revision, Clinical Modification: C17) and prevalence of lifestyle risk factors, metabolic risk factors, and inflammatory bowel disease (IBD). Risk factor associations were assessed by linear and logistic regressions. Average annual percent change was calculated using joinpoint regression. RESULTS: A total of 64,477 small intestinal cancer cases (age-standardized rate, 0.60 per 100,000) were estimated globally in 2020, with a higher disease burden found in North America (1.4). Higher small intestinal cancer incidence was associated with higher human development index; gross domestic product; and prevalence of smoking, alcohol drinking, physical inactivity, obesity, diabetes, lipid disorder, and IBD (ß = 0.008-0.198; odds ratios, 1.07-10.01). There was an overall increasing trend of small intestinal cancer incidence (average annual percent change, 2.20-21.67), and the increasing trend was comparable among the 2 sexes but more evident in the older population aged 50-74 years than in the younger population aged 15-49 years. CONCLUSION: There was a substantial geographic disparity in the burden of small intestinal cancer, with higher incidence observed in countries with higher human development index; gross domestic product; and prevalence of unhealthy lifestyle habits, metabolic disorders, and IBD. There was an overall increasing trend in small intestinal cancer incidence, calling for the development of preventive strategies.