Hematologic malignancies refer to a group of cancers that originate in the blood or bone marrow. These types of cancer affect the production, function and regulation of blood cells, including red blood cells (erythrocytes), white blood cells (leukocytes) and platelets (thrombocytes). Common examples include leukemia, lymphoma, myeloma and multiple myeloma. These conditions are often treated by hematologists or oncologists specializing in the care of patients with blood cancers.