Neuroendocrine Tumors

Malignant small bowel tumors are extremely rare, accounting for 0.1% to 0.3% of all malignancies. Fewer than 2,400 new cases of small bowel malignancy are reported in the United States each year.[1] Malignant tumors, which account for about two-thirds of all primary small bowel tumors, consist of four primary subtypes: adenocarcinoma, carcinoid tumor, lymphoma, and sarcoma (or gastrointestinal [GI] stromal tumor). Each malignancy is characterized by unique predisposing factors, anatomy, and biology. The prevalence, pattern, and relevance of both regional lymph node and distant metastases differ. As a result, the study of malignant small bowel tumors, taken as an aggregate, is fraught with difficulty.