Racial disparity in colorectal cancer: The role of ABO blood group

Background: We tested the hypothesis that racial differences that exist in the distribution of ABO blood type would partially explain the racial disparity in overall survival seen in colorectal cancer. Methods: retrospective analysis of the cancer registry of a university hospital for patients treated for colorectal cancer between 1996 and 2008. Demographic, tumor-specific, and treatment-specific variables were abstracted. We also obtained ABO blood group data. The primary end point was overall survival. We divided patients into two groups based on where they underwent surgery: the University of Arkansas for Medical Sciences (UAMS) or outside facilities. Results: Of 833 patients, 182 (21.8%) were black. There was no difference in overall survival between blacks and whites for the entire group (P = 0.61). There was a statistically significant difference in overall survival between patients at the UAMS and outside facilities (P < 0.0001). For the outside facilities group, there was a statistically significant difference in overall survival between blacks and whites (hazard ratio, CI: 1.48 [1.06-2.00]; P = 0.012); no race difference existed for the UAMS group. The ABO blood group had no effect on overall survival. On stage-stratified univariate and multivariate analyses, chemotherapy and surgery were the only statistically significant determinants of survival. Conclusions: In this study, racial differences in ABO blood group distribution had no effect on overall survival.