ABO blood group and the risk of breast cancer: Multicenter, case-control, observational study.

Abstract

1572 Background: The role of genetic factors in the development of cancer is widely accepted. ABO blood type is an inherited characteristic and previous studies have observed an association between ABO blood group and risk of certain malignancies, including pancreatic and gastric cancer. The data on the role of ABO blood group and Rh factor in breast cancer is inconclusive. Methods: All patients who had breast cancer (BC) and treated between 2000-2010 at the Departments of Medical Oncology of both Ankara and Hacettepe Universities (Ankara, Turkey) with defined ABO blood type and Rh factor were included in our retrospective reviews of tumor registry records. A group of volunteer healthy women donors of Turkish Red Crescent between 2004-2011 were identified as a control group, without any matching factors. The relationship of ABO blood types and Rh factor with various prognostic factors such as age at diagnosis, menopausal status, family history of breast cancer, and ER/PR/HER2 status were evaluated from 1740 BC patients. We compared the distributions of ABO blood types, Rh factors among 1740 patients and 204,553 healthy controls. Among BC patients, differences between each of aforementioned ABO blood groups and Rh factors with respect to various prognostic factors were explored, respectively. Results: Overall distributions of ABO blood groups as well as Rh factor were comparable between patients (44% A, 8% AB, 16% B, 32% O, 88% Rh+) and controls (41% A, 8% AB, 16% B, 35% O, 87% Rh+). However, there were statistically significant differences between patients and controls with respect to A vs. nonA (p=0.019) and marginal significance (p=0.051) for O vs. nonO. Among patients, there were statistically significant differences between A and nonA with respect to HER2 (p=0.0421), M stage (p=0.0447), T stage (p=0.0020). Only T stage (p=0.0337) were significantly different between O vs nonO. Grade (p=0.0227) and M stage (p=0.0107) were significantly different between Rh factors. Conclusions: In our study sample, ABO blood type was statistically significantly associated with breast cancer. Additional studies are necessary to determine the mechanisms by which ABO blood type may influence the risk of breast cancer.