GSTM1 and chronic kidney disease: Although most of ESA users started ESA treatment having baseline Hb values within the range recommended by the Italian guidelines (Hb < 10 g/dL in cancer and Hb < 11 g/dL in CKD), 18.5% (N = 114) of CKD patients and 10.3% (N = 48) of cancer patients started ESA treatment with baseline Hb values ≥11 g/dL.