Chronic Myeloid Leukemia (CML) is a clonal disorder thought to originate in a single abnormal haematopoietic stem cell. This myeloproliferative fatal stem cell disorder comprises
approximately 14% of all leukemias. In most cases, CML runs a triphasic course, which includes an initial chronic phase that transforms eventually into a blastic phase resembling acute leukemia. In 60%- 80% of patients, an intermediate or accelerated phase precedes the terminal blastic phase. Accelerated phase and blastic phase sometimes are lumped together and considered to be
advanced phase CML. The entire continuum from chronic phase to blastic phase lasts a median of 3 to 5 years . This time period can be broken down in to the chronic phase which if untreated,
lasts for 2 to 5 years and finally the fatal blastic phase, which lasts from 3 to 6 months. A patient can present in any of these 3 stages.