Small bowel neuroendocrine tumors: Unique features and low lethality compared with small bowel adenocarcinoma

Population-based studies comparing clinical characteristics and survival disparities between patients with small bowel adenocarcinoma (SBA) and small bowel neuroendocrine tumors (SBNETs) in the United States are limited.

Data for patients with SBA or SBNETs, obtained from the Surveillance, Epidemiology, and End Results database for the years between 2000 and 2018 were analyzed.

Between 2000 and 2018, the age-adjusted incidence of SBA experienced a marginal increase whereas SBNETs demonstrated a significant increase, emerging as the predominant subtype of small bowel cancer (SBC). Diagnoses peaked at ages 65-69 years for SBA and 60-64 years for SBNETs, with the latter exhibiting a heightened age-specific incidence and maintaining equilibrium in gender distribution. Clinicopathologic disparities revealed SBA's duodenal predilection, larger tumor size, and advanced stages, contrasting with SBNETs' ileal predilection, early-stage presentation, and superior outcomes. SBNETs patients underwent surgery more frequently but received less chemotherapy and radiation than SBA patients. Factors intricately correlated with a diagnosis of SBNETs included female gender, White race, advanced age, marital status, recent diagnoses, superior tumor differentiation, smaller size, distal location, and early-stage presentation. Survival analysis unveiled a remarkable 79% reduction in the mortality risk for SBNETs compared with SBA. Subgroup analysis further confirmed the consistently favorable survival advantages of SBNETs, highlighting the clinical relevance of histological classification in prognostication.

Compared with SBA, SBNETs exhibited distinctive clinicopathological features characterized by a higher inclination toward low-grade and early-stage manifestations, thereby contributing to superior survival outcomes.