Your blood type is more than just important for transfusions — emerging research suggests it may influence your risk of developing certain cancers. While no blood type guarantees immunity, multiple studies and meta-analyses point to blood type O as having the lowest overall risk for several common cancers compared to types A, B, and AB.
A large systematic review found that blood group A is associated with an increased risk of cancer overall, while blood group O is linked to a decreased risk.
Why Blood Type O May Offer Protection
Scientists believe the difference lies in the ABO antigens on red blood cells and how they interact with inflammation, bacteria, and immune responses:
- People with blood type O have no A or B antigens. This may make it harder for certain cancer-promoting processes (like chronic inflammation from H. pylori bacteria) to take hold.
- Types A, B, and AB carry these antigens, which some studies link to higher susceptibility to specific cancers.
Key findings from research:
- Stomach (gastric) cancer: Blood type A consistently shows higher risk (up to 38% increased in some cohorts) compared to type O. Non-O types also face elevated risk.
- Pancreatic cancer: Non-O blood types (A, B, AB) have a significantly higher risk than type O. One analysis showed type O linked to better survival and less advanced disease at diagnosis.
- Colorectal cancer: Several meta-analyses indicate blood type O provides a protective effect, while type A or AB may increase risk.
- Overall cancer risk: In large cohort studies, type O often appears as the reference with the lowest incidence for gastrointestinal cancers.
Some studies note slight variations — for example, type AB occasionally shows lower risk for kidney cancer — but across most major reviews, type O emerges with the most consistent protective pattern for the deadliest digestive cancers.
If you have blood type A, B, or AB and a family history of stomach or pancreatic cancer, discuss extra vigilance with your doctor — but again, the absolute risk increase is relatively small.
Bottom line
Research suggests blood type O has the lowest risk of developing certain cancers, particularly stomach, pancreatic, and colorectal. This protective edge likely stems from the absence of A and B antigens. However, blood type is just one non-modifiable factor among many. Focus on lifestyle choices you can control for the best protection against cancer.
