Thirty per cent of cancer patients suffer from anemia before any treatment. This anemia is caused by haematopoiesis troubles related to cytokines production and by endogenous erythropoietin deficiency. Clinically, its symptoms, including fatigue, spoils patients'quality of life. Known as a prognostic factor for several cancers, anemia also lowers radiotherapy or chemotherapy efficiency by tumor hypoxia. Recombinant EPO restores normal haemoglobin level, quality of life and treatment efficiency.