MedWire News: Study results show that people with blood group A have a higher incidence of gastric cancer and those with blood group O an increased risk for peptic ulcers compared with those with other blood types.
These findings confirm previously suggested, but not conclusively proven, associations between blood groups A and O and these disorders.
Gustaf Edgren (Karolinska Institutet, Stockholm, Sweden) and colleagues used the Scandinavian Donations and Transfusions database (SCANDAT) to identify the blood groups of 1,089,022 blood donors with a mean age at first donation of 33.4 years.
The donors were then followed up for 35 years - from first donation until death or 2002 - during which time 688 gastric cancers and 5667 peptic ulcers were recorded.
The team found that blood group A was associated with a significant 20% increase in gastric cancer incidence compared with blood groups O and B. People with blood group AB also had a slightly increased risk for gastric cancer compared with those with blood group O or B, but this was not statistically significant.
Conversely, blood groups A, B, and AB were associated with a significantly decreased incidence of duodenal (by 15-25%) and gastric (by 9-23%) ulcers compared with blood group O.
"In addition to confirming that individuals with blood group A are at a slightly increased risk of stomach cancer, we have, quite strikingly, also shown that individuals with blood group O have a clearly elevated risk… for gastric and duodenal ulcers compared with the other blood groups," write Edgren et al.
"Although no definitive conclusions can be drawn from this strictly observational investigation, with no access to data about Helicobacter pylori infection, a possible explanation is that these observations may result from different susceptibilities and immunologic responses to such infection," they conclude in the American Journal of Epidemiology.
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