While most people consider blood type only relevant for transfusions, research shows it can also signal susceptibility to certain diseases.
A 2019 study in BMC Cancer analyzed 4,932 gastric‑cancer patients and 6,158 controls to examine ABO blood groups and cancer risk. The authors found that individuals with type A blood carried a 13 % higher risk of stomach cancer compared with type O, and type AB carried an 18 % higher risk. A meta‑analysis of related studies confirmed similar patterns: a 19 % increased risk for type A and a 9 % increase for type AB.
The authors also noted that type A blood is linked to higher susceptibility to Helicobacter pylori, the primary cause of gastric cancer. Importantly, the study showed the risk remained elevated for type A even in the absence of an H. pylori infection, while the risk for type AB rose only when the infection was present.
Having blood type A or AB does not guarantee that you will develop stomach cancer. Genetics is only one piece of the puzzle. Age, sex, ethnicity, smoking, alcohol, high‑salt diets, and even environmental changes also influence risk.
Gastric cancer remains the fifth most common cancer worldwide and the third leading cause of cancer death. The American Cancer Society projects 30,300 new U.S. cases and 10,780 deaths in 2025. Fortunately, a 2024 BMC Public Health study reports a decline in incidence and mortality over the past decade in many regions, although population growth may offset these gains.
Knowing your blood type can help you engage in informed conversations with your healthcare provider and adopt preventive measures—regular screenings, balanced nutrition, and avoiding tobacco and excess alcohol.
