Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder. This disease affects myeloid, monocytic, erythroid, megakaryocytic, B-cell and T-cell lineages. CML constitutes 15% of all leukemias with a median age of 66 years, and incidence rising with age. Ionizing radiation appears to be the only environmental risk factor. CML cannot be inherited and is not preventable. The majority of cases (90%) are due to a consistent chromosome abnormality involving a translocation, resulting in the Philadelphia Chromosome and the fusion gene BCR-ABL.
CML is divided into 3 phases based on clinical characteristics. It usually begins with a chronic phase, progressing to an accelerated phase and finally to a blast crisis. Most drugs are instated during the chronic phase. Interferon alfa was the main drug used for CML before the introduction of Imatinib which has changed CML treatment dramatically, and enabled patients to have a good quality of life in comparison.