Chronic myelogenous (or myeloid or myelocytic) leukemia (CML), also known as chronic granulocytic leukemia (CGL), is a cancer of the white blood cells. It is a form of leukemia characterized by the increased and unregulated growth of predominantly myeloid cells in the bone marrow and the accumulation of these cells in the blood. CML is a clonal bone marrow stem cell disorder in which a proliferation of mature granulocytes (neutrophils, eosinophils and basophils) and their precursors is found. It is a type of myeloproliferative disease associated with a characteristic chromosomal translocation called the Philadelphia chromosome. CML is now largely treated with targeted drugs called tyrosine kinase inhibitors (TKIs) which have led to dramatically improved long-term survival rates since the introduction of the first such agent in 2001. These drugs have revolutionized treatment of this disease and allow most patients to have a good quality of life when compared to the former chemotherapy drugs. In Western countries, CML accounts for 15-25% of all adult leukemias and 14% of leukemias overall (including the pediatric population, where CML is less common