Are the stages of chronic myelogenous leukemia important? They are, because the doctor must know at which stage the disease has developed to determine the therapy the patient will undergo. For instance, the treatment in the first stage will be different than the second stage depending on different factors. The stages of this disease are considered as phases instead, which are three phases. The phases of CML are chronic phase, accelerated phase, and blastic crisis. The first phase is the chronic phase. Patients in this phase have less than 10% of immature white blood cells. The symptoms are mild with frequent infections, tiredness, and indigestion. The main treatment is a tyrosine kinase inhibitor (TKI) such as imatinib, nitotinib, or dasatinib.