Epidemiological and clinical trends of malignant small-bowel tumors in Asia.

Malignant small-bowel tumors are uncommon, accounting for < 5% of all gastrointestinal cancers, yet their incidence has exhibited a steady rise in both Western and Asian populations. This increase is attributed to expanded use of advanced diagnostic modalities and improved registry completeness. Malignant small-bowel tumors encompass a heterogeneous group-adenocarcinoma, neuroendocrine tumors, gastrointestinal stromal tumors, and lymphoma-each with distinct anatomic predilections, molecular characteristics, and clinical behavior. In Asia, sporadic adenocarcinoma remains the predominant subtype, whereas Crohn's disease-associated lesions and small-bowel neuroendocrine tumors are relatively less common than in Western cohorts. Early detection continues to be limited by diagnostic delays caused by nonspecific symptoms and the anatomic inaccessibility of the small-bowel. Prognosis varies substantially across subtypes, with adenocarcinoma demonstrating the poorest survival rate despite advances in systemic therapy. Recent nationwide and multicenter studies from Asian countries have highlighted evolving temporal trends, improvements in diagnostic performance, and emerging regional differences in etiology, stage distribution, and outcomes. A clearer understanding of the epidemiologic patterns and clinical charimacteristics of malignant small-bowel tumors in Asia is essential for developing region-specific diagnostic strategies, optimizing treatment pathways, and prioritizing areas for future collaborative research.