It may be due to the fact that classifications of anemia differ somewhat from several references; the World Health Organization explains anemia as an Hb level < 10.9 g/dL (15), whereas the European Organization for Research and Treatment of Cancer (EORTC) and the National Cancer Institute (NCI) (16) describe anemia as a Hb level < 12.0 g/dL (28). This evidence concerns the gene GSTM1 and anemia.