Background: For decades, studies have been performed to evaluate the association between ABO blood groups and risk of cancer. However, whether ABO blood groups are associated with overall cancer risk remains unclear. We therefore conducted a meta-analysis of observational studies to assess this association. Materials and Methods: A search of Pubmed, Embase, ScienceDirect, Wiley, and Web of Knowledge databases (to May 2013) was supplemented by manual searches of bibliographies of key retrieved articles and relevant reviews. We included case-control studies and cohort studies with more than 100 cancer cases. Results: The search yielded 89 eligible studies that reported 100,554 cases at 30 cancer sites. For overall cancer risk, the pooled OR was 1.12 (95%CI: between ABO blood groups and overall cancer risk still remains unclear. Therefore, we conducted a systematic review and meta-analysis to evaluate the association between ABO blood groups and overall cancer risk, as well as the risk of individual cancer sites.1
Materials and Methods
Search strategyWe performed a systematic literature search (up to May 2013) of Pubmed, Embase, ScienceDirect, Wiley, and Web of Knowledge for studies reporting the association between ABO blood groups (self-reported or lab tested) and cancer risk. In addition, we searched the reference lists of relevant articles and reviews. Only articles published in English were considered. Two search themes were combined using the Boolean operator 'and'. The first theme, cancer, combined exploded versions of the Medical Subject Headings (MeSH) cancer, tumor, carcinoma, neoplasm or malignancy. The second theme, blood group, combined exploded versions of MeSH terms blood group, or blood type.
