Distinct patterns of chronic gastritis associated with carcinoid and cancer and their role in tumorigenesis.

A series of 60 gastric endocrine tumors comprised 44 body-fundus argyrophil carcinoids, of which 23 arose in a background of hypergastrinemia and type A chronic atrophic gastritis (A-CAG), mainly with histologic patterns suggestive of an autoimmune process. Only 22 percent (compared with 19 percent of 58 tumor-free A-CAG cases) of 36 carcinoids and 21 percent of 19 A-CAG carcinoids investigated had Helicobacter pylori (HP) colonization, against 50 percent of 14 CAG-associated neuroendocrine carcinomas or mixed endocrine-exocrine tumors, 84 percent of 150 cases with early gastric cancer (p < 0.001 versus carcinoids), mostly with B- or AB-type CAG, 76 percent of 97 tumor-free AB-CAG, and 95 percent of 151 tumor-free B-CAG cases. Secondary hypergastrinemia and local mechanisms activated by chronic autoimmune gastritis are among factors involved in the pathogenesis of relatively indolent CAG-associated carcinoids, whereas active HP gastritis in cooperation with environmental carcinogens may likely cause more severe epithelial transformation, leading to ordinary cancer and, possibly, to neuroendocrine carcinomas or mixed endocrine-exocrine tumors.