1. ¹Division of Cancer Epidemiology and Genetics, National Cancer Institute, 6120 Executive Blvd, Rm 3034, Bethesda, MD 20892-7232, USA
2. ²Department of Cancer Epidemiology, Cancer Institute of the Chinese Academy of Medical Sciences, PO Box 2258, Beijing, 100021 China
3. ³Department of Medicine, New York University School of Medicine, New York, NY, USA
4. ⁴Department of Microbiology, New York University School of Medicine, New York, NY, USA
5. ⁵Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, CO, USA

Correspondence: Dr F Kamangar, E-mail: kamangaf@mail.nih.gov; Dr YL Qiao, E-mail: qiaoy@public.bta.net.cn

Received 16 August 2006; Revised 16 October 2006; Accepted 10 November 2006; Published online 19 December 2006.

Abstract

In a cohort of 29 584 residents of Linxian, China, followed from 1985 to 2001, we conducted a case–cohort study of the magnitude of the association of Helicobacter pylori seropositivity with cancer risk in a random sample of 300 oesophageal squamous cell carcinomas, 600 gastric cardia adenocarcinomas, all 363 diagnosed gastric non-cardia adenocarcinomas, and a random sample of the entire cohort (N=1050). Baseline serum was evaluated for IgG antibodies to whole-cell and CagA H. pylori antigens by enzyme-linked immunosorbent assay. Risks of both gastric cardia and non-cardia cancers were increased in individuals exposed to H. pylori (Hazard ratios (HRs) and 95% confidence intervals=1.64; 1.26–2.14, and 1.60; 1.15–2.21, respectively), whereas risk of oesophageal squamous cell cancer was not affected (1.17; 0.88–1.57). For both cardia and non-cardia cancers, HRs were higher in younger individuals. With longer time between serum collection to cancer diagnosis, associations became stronger for cardia cancers but weaker for non-cardia cancers. CagA positivity did not modify these associations. The associations between H. pylori exposure and gastric cardia and non-cardia adenocarcinoma development were equally strong, in contrast to Western countries, perhaps due to the absence of Barrett's oesophagus and oesophageal adenocarcinomas in Linxian, making all cardia tumours of gastric origin, rather than a mixture of gastric and oesophageal malignancies.