Gastric MALT lymphoma is a rare type of non-Hodgkin lymphoma that is characterized by the slow multiplication of B lymphocytes, a type of immune cell, in the stomach lining. This cancer represents approximately 12 percent of the extranodal (outside of lymph nodes) non-Hodgkin lymphoma that occurs among men and approximately 18 percent of extranodal non-Hodgkin lymphoma among women (28). During the period 1999–2003, the annual incidence of gastric MALT lymphoma in the United States was about one case for every 100,000 persons in the population.
Normally, the lining of the stomach lacks lymphoid (immune system) tissue, but development of this tissue is often stimulated in response to colonization of the lining by H. pylori (2). Only in rare cases does this tissue give rise to MALT lymphoma. However, nearly all patients with gastric MALT lymphoma show signs of H. pylori infection, and the risk of developing this tumor is more than six times higher in infected people than in uninfected people (29, 30).