Small bowel nonendocrine neoplasms: current concepts and novel perspectives

Although small bowel nonendocrine neoplasms are rare, their incidence has increased dramatically over the past 30 years. Small bowel malignacies can be classified depending upon their cellular origin into four principal histotypes: carcinoid tumors, adenocarcinomas, lymphomas and mesenchymal tumors. Until a few years ago, the treatment of small bowel tumors had remained relatively unchanged, with little progress in the development of effective adjuvant therapies and in the improvement of long-term survival over time. Recently, the growing interest in the understanding of the mechanisms underlying carcinogenesis has offered novel insights for the diagnosis and therapy of small bowel tumors. This review summarizes the state-of-the-art of small bowel nonendocrine tumors and the recent advancements in the knowledge of their molecular pathogenesis and cellular origin, with particular emphasis on stem cell research field.