On the mechanism behind the association between ABO blood groups and gastric carcinoma.

It has been hypothesized that the mechanisms behind the association between blood group A and gastric carcinoma is that the carcinoma cells produce an antigen immunologically related to blood group A, which particularly in O-individuals may have a protective effect by preventing the growth and spread of the tumour. The hypothesis predicts that O-individuals would have a longer survival time than A-individuals and that eventually the protective effect in blood group O would be somewhat stronger in women with multiple pregnancies. The results showed a significantly lower frequency of blood group O in females and a tendency towards a longer survival time in O-individuals among gastric cancer patients, but the relationship between blood group O and number of children was not in the expected direction. Thus the observations gave only partial support for the hypothesis that the association between ABO blood groups and gastric carcinoma is dependent on the antigenicity of the neoplasm. The data showed a significantly higher prevalence of gastric carcinoma and a lower average survival time in male patients.