[The association between Helicobacter pylori and gastric neoplasia. Epidemiologic evidence]

Helicobacter pylori (HP) causes chronic gastritis and, together with non-steroidal anti-inflammatory drugs, is considered the most frequent etiologic agent of peptic ulcer. Since there are numerous epidemiologic and pathogenesis studies that demonstrate an association between infection by HP and gastric neoplasias, the World Health Organization declared, in 1994, HP infection a Group 1 carcinogen (a definitive cause of human neoplasias, similar to tobacco). This article reviews the epidemiological evidence supporting the association between HP infection and two gastric neoplasias: adenocarcinoma and B cell lymphoma associated to mucosas (MALT). This article also presents preliminary results of a project performed in the mountainous region of Chiapas, Mexico, in which the decrease of precancerous gastric lesions were studied one year after treatment for HP infection.