Helicobacter pylori and gastric cancer

• Helicobacter pylori is a Gram-negative, spiral-shaped bacterium that has adapted to survive in the harsh acidic environment of the human stomach
• there is evidence of a causal association between H.pylori and cancer of the gastric corpus and antrum (1,2)
• the incidence of gastric cancer of the gastric corpus and gastric antrum are declining in areas where H.pylori infection is becoming less prevalent
• virulent strains of H pylori producing VacA or CagA cause indirect inflammation of the gastric mucosa and direct epigenetic changes in the epithelial cells, promoting malignant transformation (3)
• prophylactic eradication of H pylori after endoscopic resection of early gastric cancer helps to prevent the development of metachronous gastric carcinoma (2)
• less than 5% of individuals with H pylori infection will develop gastric cancer (3)

The ACG Clinical Guideline lists specific indications for H. pylori testing and treatment(4):

1. Benign / non-cancer conditions

• peptic ulcer disease (active or past)
• gastric MALT (mucosa-associated lymphoid tissue) lymphoma, low-grade B-cell
• uninvestigated dyspepsia: patients < 60 years old, without alarm features
  • for high-risk gastric cancer populations, a lower age threshold (~45–50 years) may be used
• functional dyspepsia (symptoms without structural disease)
• adult household members of someone who tests positive (non-serological) for H. pylori
• long-term NSAID users, or people starting low-dose aspirin therapy
• unexplained iron deficiency anaemia (IDA)
• idiopathic (autoimmune) thrombocytopenic purpura (ITP)

2. Premalignant / Malignant / Cancer-Prevention Conditions
(“Primary and secondary prevention of gastric adenocarcinoma”)
This includes:

• people with gastric premalignant conditions (GPMC): such as atrophic gastritis, intestinal metaplasia, dysplasia
• people with history of early gastric cancer (resection)
• those with prior or current gastric adenocarcinoma
• people with gastric adenomas or hyperplastic polyps, since these often occur in inflamed mucosa.
• first-degree relatives of gastric cancer patients.
• individuals at increased risk of gastric cancer based on ethnicity, geography, or hereditary risk (e.g. immigrants from high-incidence regions).
• autoimmune gastritis

Reference:

1. Drug and Therapeutic Bulletin (1998); 36 (8): 57-9.
2. Fukase K, Kato M, Kikuchi S, Inoue K, Uemura N, Okamoto S, Terao S, Amagai K, Hayashi S, Asaka M; Japan Gast Study Group.Effect of eradication of Helicobacter pylori on incidence of metachronous gastric carcinoma after endoscopic resection of early gastric cancer: an open-label, randomised controlled trial. Lancet. 2008 Aug 2;372(9636):392-7.
3. Ghaffar S A, McCarter M D, Kim S S, Bilal M, Del Chiaro M, Mungo B et al. Advances in the management of gastric cancer.BMJ 2025; 391.
4. Chey WD, Howden CW, Moss SF, Morgan DR, Greer KB, Grover S, Shah SC. ACG Clinical Guideline: Treatment of Helicobacter pylori Infection. Am J Gastroenterol. 2024 Sep 1;119(9):1730-1753.