Clinical and Histopathological Correlations With Blood Groups in Patients With Gastric Cancer.

Introduction Gastric cancer results from intricate gene-environment interactions, and defining both modifiable and inherited risk factors could improve prevention and personalised therapy. Although ABO blood groups have been linked to gastric cancer susceptibility, findings are inconsistent. Materials and methods We retrospectively compared 214 histologically confirmed gastric cancer cases with 214 age- and sex-matched healthy controls. Presenting symptoms, physical findings (palpable mass, jaundice, ascites, hepatomegaly) and upper-gastrointestinal bleeding were recorded. Endoscopy documented tumour location (cardia, corpus, antrum, incisura angularis, whole stomach) and Borrmann type. Biopsies were classified as adenocarcinoma, signet-ring cell carcinoma, neuroendocrine tumour or lymphoma. ABO blood group was determined serologically, and tumour-node-metastasis (TNM) stage assigned by imaging. Results The cancer cohort comprised 149 men and 65 women and the control group 107 men and 107 women. ABO distributions were as follows: A, 50.5 %; B, 16.8 %; AB, 2.8% and O, 29.9 % in cases, versus 43.0%, 16.4%, 8.0% and 32.6% in controls, respectively. Blood group A showed a non-significant excess risk, whereas AB showed a non-significant deficit (p>0.05). Epigastric pain occurred significantly more often in AB and O groups than in A and B groups (p<0.05). No other clinical, endoscopic, histological or staging variables differed by blood group. Conclusions Our findings suggest a potential increase in gastric cancer risk associated with blood group A, and a possible protective effect of group AB, although statistical significance was not achieved. These observations underscore the need for larger, multicentre prospective studies incorporating genetic and environmental factors to clarify the mechanistic role of ABO antigens in gastric carcinogenesis and to improve risk stratification and early detection strategies.