GSTM1 and breast cancer: Preoperative anemia, even mild anemia, has been shown as an independent factor associated with an increased risk of morbidity and mortality in patients undergoing major non-cardiac and cardiac surgery.1,2 Preoperative anemia is usually regarded as a risk factor because of its association with increased perioperative transfusions of blood components.3,4 Breast cancer patients are at risk of anemia and interestingly, decreased hemoglobin (Hb) levels are reportedly correlated with poor treatment outcomes and survival in patients of breast cancer.5-7