The medical oncologist is the specialist treating the cancer patient. Its aim is the care of the patient from diagnosis, including treatment and follow-up until healing or during terminal illness. Attend the pathology associated with tumor disease, and treatment complications. Collaborates actively in the emotional, social and psychological development of patients and their families. It addresses especially the handling of antineoplastic drugs, among others, the cytostatic or chemotherapy, and must possess a broad knowledge of their pharmacokinetics and interactions with other drugs.