What research says about blood type and cancer risk
-
A large meta‑analysis (pooling many studies) found that people with blood type O tend to have a lower overall cancer risk compared with non‑O blood types. PubMed
-
For specific cancers: this meta-analysis reported a reduced risk for people with type O blood for stomach (gastric), pancreatic, breast, colorectal (colon), esophagus, ovarian, and nasopharyngeal cancers. PubMed+1
-
Another recent meta‑analysis focusing on colorectal cancer found that type O blood was associated with a statistically lower risk of colorectal cancer compared with other blood groups. journal.waocp.org+1
-
Some cohort studies show that for general cancer incidence, people with blood type B had a slightly lower risk compared to blood type A. PubMed+1
-
For certain cancers (for example Thyroid cancer in one recent study), individuals with blood type O had lower rates of aggressive disease features (e.g. lymph node invasion, capsular invasion) compared to non‑O groups. SpringerLink
Bottom line from research so far: Blood type O appears, in many studies, to be associated with a somewhat lower risk — or less severe forms — of certain cancers, especially gastrointestinal and colorectal cancers. But: the magnitude of difference is modest, and associations vary by cancer type and population studied.
⚠️ Why results are not definitive — and what to keep in mind
-
Not all studies agree. Some find no significant association between blood type and certain cancers (e.g. breast or cervix) in specific populations. PubMed+1
-
Observational studies can show correlation — but cannot prove that blood type causes higher or lower cancer risk. Many other factors (genetics, lifestyle, environment, diet, access to health care, etc.) play much larger roles.
-
Even a “lower risk” does not mean “no risk.” People with type O (or any type) can — and do — still develop cancer.
-
Risk differences (when present) tend to be modest. For example, the reduced odds for colorectal cancer in type O vs non‑O is small (OR around 0.93 in one meta‑analysis). journal.waocp.org+1
🩺 What doctors recommend regardless of your blood type
Because blood type is only a very small factor — and not one you can change — medical advice focuses on modifiable factors that strongly influence cancer risk.
-
Eat a balanced, healthy diet — rich in fruits, vegetables, whole grains; avoid excessive processed/red meat.
-
Maintain healthy weight and physical activity.
-
Avoid tobacco (smoking, smokeless), limit alcohol.
-
Get regular health check‑ups and age‑appropriate cancer screenings (especially if you have family history or other risk factors).
-
Address other risk factors: chronic infections, environmental exposures, occupational hazards.
-
Stay informed — keep up with recommended medical screenings and healthy lifestyle choices.
✅ Conclusion — What we know, and what we don’t
-
There is some scientific support for blood type O (and sometimes B) having slightly lower risk for certain cancers, according to population studies and meta‑analyses.
-
However, this link is weak, inconsistent, and insufficient to treat blood type as a reliable “protection.”
-
The best way to reduce cancer risk remains healthy lifestyle choices, regular checkups, and preventive care — regardless of your blood group.