GSTM1 and Thromboembolism: ESA treatment for renal anemia in pre-dialysis CKD patients with a history of cancer can be considered, while taking into consideration patients’ wishes and when the benefits of treatments such as reduced amount of blood transfusion and iron replacement outweigh the harmful effects of thromboembolism and recurrence/new occurrence of cancer, following a careful course of treatment and monitoring to avoid high Hb levels.