The Association between ABO Blood Group and the Risk of Colorectal Cancer: A Systematic Literature Review and Meta-Analysis

INTRODUCTION: Recently, studies have investigated the relationship between blood types and cancers. Contradictory results regarding the relationship between blood group type and colorectal cancer(CC) have been reported. The purpose of this study was to systematically investigate the distribution of ABO blood group frequency and evaluate its relationship with CC. MATERIAL AND METHODS: To conduct this systematic meta-analysis, we searched PubMed, Scopus, Web of Science, and Google Scholar databases using appropriate MESH terms until July 2022. All observational studies which assessed the ABO blood group frequency distribution and the association between ABO and CC were included. The Risk of Bias Assessment tool was used to assess the quality of studies. A random model was used to estimate the odds ratio (OR). The Egger test was used to assess the publication bias. RESULTS: Overall,14 studies (413,132 patients) were included. According to the pooled estimation, blood groups A, B, AB, and O frequency in patients with CC were 37%,18%,9%, and 31%, respectively. The OR of CC in people with the A blood group was higher than in the other groups (OR: 1.11, 95% CI:1.03,1.19, P:0.001). In contrast, the OR of CC in people with the O blood group was significantly lower than in other blood groups (OR: 0.93, 95% CI:0.83,0.97, P:0.001). No significant relationship was observed for B and AB blood groups with CC. CONCLUSIONS: This Meta-analysis showed that blood group type A has a greater risk of developing CC, while blood group type O was associated with lower chances of CC.