Risk of Breast Cancer According to Glycaemia and HbA1c Concentration—A Meta-analysis of Prospective Studies

Some observational studies have suggested that women with diabetes may be at increased risk of breast cancer. Blood levels of fasting glucose (FG) and of glycated hemoglobin (HbA1c) are major diagnostic tools for diabetes. The aim of this study was to investigate the association between HbA1c, FG and breast cancer occurrence. A systematic literature search identified prospective studies which reported a quantitative estimate of the association between HbA1c or FG and breast cancer. Summary relative risks (SRR) of breast cancer, comparing high vs. low levels of HbA1c or FG, were computed using random-effect meta-analysis. Ten studies for HbA1c (116,035 women and 3,095 breast cancer cases) and 13 studies for FG (971,071 women and 14,579 breast cancer cases) were selected. High levels of HbA1c (FG) ranged from u003e4.5% to u003e9% (u003e5 to u003e7.8 mmol/L), and low level ranged from 2 =0%). No study was found on FG among diabetic women only. No association was found between HbA1c and breast cancer occurrence, while fasting glucose might be associated with a slight increased risk. The lack of clear association suggests that the increased risk of breast cancer observed among diabetic women appears to be driven by factors other than the blood glucose concentration disorders. Disclosure A. Macacu: None. C. Pizot: None. P. Boyle: Other Relationship; Self; Sanofi. P. Autier: Other Relationship; Self; Sanofi.