What are the major risk factors for gastric adenocarcinoma?

Helicobacter pylori, diet (nitroso compounds, high salt, smoked/pickled food, low fruit/vegetable), smoking, obesity, pernicious anaemia and atrophic gastritis, previous gastric surgery, blood group A, Menetrier's disease, and family cancer syndromes (Lynch, FAP). Far-Eastern geography and male sex add risk.

Clinical relevance. Knowing risk factors targets prevention (H. pylori eradication, diet) and identifies who to suspect.

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Risk factors for gastric cancer

Gastric cancer risk reflects an interplay of infection, diet, host, and environmental factors.

Infection and inflammation

• H. pylori (the dominant modifiable factor)
• Pernicious anaemia/autoimmune atrophic gastritis; previous gastric surgery (reduced acidity, bile reflux)

Diet and lifestyle

• Nitroso compounds, high salt, smoked food, salted fish, pickled vegetables; low fruit and vegetable intake
• Smoking (hazard ratio ~2-3), obesity

Host and genetic

• Blood group A; Menetrier's disease (hypertrophic gastropathy)
• Family cancer syndromes: Lynch (HNPCC), familial adenomatous polyposis; hereditary diffuse gastric cancer (E-cadherin)
• Male sex; peak age 65-80

Geography

• High incidence in the Far East (e.g. Japan); immigrants retain native-country risk, while their offspring approach the risk of the new country.