Cancers of the blood, sometimes referred to as hematologic malignancies, are disorders of bone marrow cells that lead to the failure of the normal function of bone marrow and the uncontrolled growth of cancerous cells in the bone marrow. These cancerous cells can spill over into the bloodstream and affect other organs causing widespread symptoms. The disease is life threatening because it blocks the normal function of the marrow, which is to produce red cells (preventing anemia), white cells (preventing infection), and platelets (preventing progression).