According to the ESMO guidelines, those with Hb 10-11 g/dL are recommended to be administered 1,000 mg of iron intravenously if TSAT is less than 20% or serum ferritin is less than 100 ng/mL, whereas those with Hb 8-10 g/dL without vitamin B12 and folate deficiency are recommended to receive intravenous iron if serum ferritin is less than 100 ng/mL or TSAT is less than 20% [4]. This evidence concerns the gene GSTM1 and folate deficiency.