ABO and gastric adenocarcinoma: In a study conducted by Nozoe and Colleagues in 284 patients, non-O blood groups correlated with poorly differentiated grades of the tumour and AB blood group was associated with advanced stage and large tumour size, the significance of ABO blood group distribution might be associated with biological behavior of gastric adenocarcinoma patients, but no correlation was found between different ABO blood groups and overall survival 18.