Prognostic value of ABO blood types in young patients with breast cancer; a nationwide study in Korean Breast Cancer Society.

The purpose of this study was to investigate the relationship between ABO blood types and breast cancer survival in young Korean patients. This was a retrospective study of 115,474 patients who were surgically treated for primary breast cancer between 1987 and 2011 in Korea. All data were collected by the Korean Breast Cancer Society (KBCS) online breast cancer registry. Each hospital serologically examined the ABO blood types of patients before surgery. There was no significant difference in overall survival (OS) or breast cancer-specific survival (BCSS) among ABO blood types. Type of surgery; T stage; N stage; histologic grade; status of estrogen receptor, progesterone receptor, and HER2; and chemotherapy were significant prognostic factors of OS and BCSS in univariate analysis and multivariate analyses. Compared to women with blood type O, there was a difference in OS and BCSS for blood type A, blood type B, or blood type AB. Compared to blood group non-O, patients with blood group O were more likely to have favorable prognosis when younger than 40 years. Further follow-up studies are necessary to clarify the role of the impact of ABO blood types on prognosis of breast cancer.