[Skip to Content]
[Skip to Content Landing]
January 14, 2004

Helicobacter pylori Infection and Gastric Cancer—For Want of More Outcomes

Author Affiliations

Author Affiliations: Departments of Medicine and Health Research and Policy, Stanford University, Stanford, Calif (Dr Parsonnet); and Unit of Epidemiology and Health Services Research, Medical School, University of Leeds, Leeds, England (Dr Forman).

JAMA. 2004;291(2):244-245. doi:10.1001/jama.291.2.244

In 1994, Helicobacter pylori was declared a type 1 carcinogen—a definite cause of human cancer—by the International Agency for Research on Cancer (IARC).1 This conclusion, which was based largely on epidemiological data that were later substantiated,2 left behind unsettling questions. First, some latent concern lingered that H pylori was merely a marker for other exposures. Despite subsequent studies in animals, humans, and tissue cultures indicating plausible mechanisms for H pylori–induced carcinogenesis, naysayers have clung to the small, residual probability that H pylori is merely a confounder for the true cause of disease. Because H pylori infection is so closely linked to socioeconomic status, such confounders are not difficult to find.