The Impact of ABO Blood Type on Developing Venous Thromboembolism in Cancer Patients: Systematic Review and Meta-Analysis.

The impact of ABO blood type in the development of venous thromboembolism in cancer patients remains controversial. To develop a sense of the current opinion in this area, we conducted a systematic review and meta-analysis. In March 2021, we performed a systematic search of PubMed, the Cochrane library, and Scopus for studies that compared cancer patients who had a blood type of either O or non-O (A, B, and AB). Our objective was to use multivariate logistic regression analysis to determine how ABO blood type was associated with the development of venous thromboembolism. Our selection criteria were met by a total of nine studies in 25,884 patients for the systematic review and five studies in 22,777 patients for the meta-analysis. In cancer patients, we found that non-O blood type was associated with a nearly two-fold increase in risk of venous thromboembolism (pooled OR: 1.74, 95% CI: 1.44-2.10). Additionally, among the eligible patients, 21,889 patients were post-operative urological cancer patients. In these patients, the analysis also showed an association between non-O blood type and increasing risk of venous thromboembolism after pelvic surgery for malignancy (pooled OR: 1.73, 95% CI: 1.36-2.20). Our meta-analysis suggested that non-O blood type is a risk factor for venous thromboembolism among patients with cancer. As blood type is routinely determined preoperatively by objective and standardized methods, we anticipate that our results will be useful for managing venous thromboembolism in cancer patients, especially after pelvic surgery for urological cancers.