Helicobacter pylori and its Association with Gastric and Oesophageal Carcinomas

University dissertation from Institutionen för kliniska vetenskaper, Lunds universitet

Abstract: Helicobacter pylori is one of the most common infections in man. The infection is often acquired during childhood and usually results in a chronic life-long inflammation in the gastric mucosa. The aim of our studies was to investigate the association between H. pylori seropositivity and the development of gastric and oesophageal carcinomas. Nested case-control studies were performed in the Malmö Preventive Medicine cohort consisting of 32,906 subjects. Tumour cases were identified by the Swedish National Cancer Registry. H. pylori infection was identified serologically by an in-house ELISA and a commercial Western blot method, Helicoblot 2.1. The more virulent H. pylori cagA-positive strain was identified by the CagA band in Helicoblot 2.1. We found that H. pylori seropositivity was associated with a higher risk of non-cardia gastric adenocarcinoma. H. pylori seropositivity was a risk factor for non-cardia gastric adenocarcinoma among both smoking and non-smoking subjects. CagA seropositivity was a risk factor for non-cardia gastric adenocarcinoma in the H. pylori seropositive subgroup. The size of our material did not allow the estimation of the association between H. pylori seropositivity and oesophageal adenocarcinoma or oesophageal squamous cell carcinoma, however, there was an inverse tendency associated with oesophageal squamous cell carcinoma. The Helicoblot 2.1 CagA band was evaluated in subjects with no known gastric or oesophageal malignancy. The CagA band had a bimodal peak intensity distribution. The changes in seroprevalence with year of birth suggested that CagA seropositivity was false-positive in a major proportion of H. pylori seronegative subjects when identified by Helicoblot 2.1.