Gastrointestinal endocrine tumors: Recent developments

Endocrine tumors of the gastrointestinal tract are a heterogeneous population of neoplasms differing from each other by their secretory and functional properties, pathogenetic mechanisms, related clinical syndromes, pathological associations, and prognosis. Although such heterogeneity and the relative rarity of these tumors hamper systematic investigations, significant advances in several aspects of tumor pathology have been achieved in recent years. This article focuses on the genetic background of tumor development with emphasis on the role of the MEN-1 oncosuppressor gene in either MEN-1-associated or sporadic endocrine tumors, on the identification and pathologic relevance of tumor-produced growth factors, and on the mechanism of induction of gastrin-dependent ECL cell carcinoids of the stomach.