They hypothesized that the ABO blood group antigens and the Rhesus factor may influence on survival by various moleculobiologic mechanisms: the ABO antigen expression on the urothelium, the location of ABO blood group on the long arm of chromosome 9 –a commonly altered region in bladder cancer, the encode of ABO gene on specific glycosyl transferases, followed by abnormal glycosylation of cell surface proteins, and then, modulation of epithelial-mesenchymal transition for cancer development and progression. Here, ABO is linked to cancer.