Is Helicobacter Pylori Infections in Immunocompromised Children a Risk Factor for Cancer

Helicobacter pylori (H. pylori) has been classified as a carcinogenicpathogen (1). Its prevalence is high in developing countries. A part from the gastro-intestinal pathological changes caused by this organism, reports on the association between H. pylori infection and extra gastro-intestinal diseases have been increasing (2). Although impaired host immunity should be associated with a high prevalence of this infection, a definitive relationship has not been established. In this study a cross-sectional study had been conducted to determine the prevalence of H. pylori infection in immunocompromised Thailand children (3). From 2003 to 2004, a total of 60 children <18 years of age, who received corticosteroids, immunosuppressive drugs, or both, were enrolled consecutively into this study. Patients who had taken proton pump inhibitors and antimicrobial drugs 2 weeks before the study began were excluded. Stool specimens were collected and immediately stored at – 20° C before analysis with the H. pylori stool antigen test (4). Although no study has validated this test in Thai children, most studies report its high sensitivity and specificity (>90%).The study reported a significant relation of H. pylori and childhood cancer with 16.6% among children with cancer and only 3.3% among those without cancer (2,5). Helicobacter pylori infection seems to be associated with an increased risk of developing gastric cancer. However, only a small number of infected individuals will develop gastric cancer (6), including mucosa-associated lymphoid tissue lymphoma and adenocarcinoma. The infection is contracted primarily in childhood and infection from childhood appears to enhance the risk for carcinogenesis (7). In 1994 Helicobacter pylori was classified as a group 1 carcinogen for gastric cancer by the International Agency for Research on Cancer (1). The colonization with H. pylori determine the development of gastric atrophy, also called multifocal atrophic gastritis. This involves loss of gastric ABSTRACT