Leukemia Chronic Myelogenous Stages

Chronic myelogenous leukemia (also called CML or chronic myeloid leukemia) prognosis depends, in part, on the leukemia stage seen at the time of diagnosis. Chronic leukemia stages differ depending on the type of leukemia, and oncologists assign three distinct stages to chronic myeloid leukemia: the chronic phase, an accelerated phase, and the blast crisis, or blast phase.

Chronic Leukemia Stages

Most cases of chronic myeloid leukemia are detected during the chronic phase. During the chronic leukemia stage, relatively few blast cells (very immature cells) are present in blood or bone marrow. Chronic myeloid leukemia stages can last from months to years.

Blast cells are immature blood cells. An early blast cell has the capacity to mature into either red or white blood cells. In cases of CML, blast cells develop into abnormal white blood cells. Blast cell counts are higher than normal in the chronic phase of CML, but not present in sufficient amounts to cause serious symptoms.

Chronic leukemia stages produce few symptoms. Patients may develop an enlarged spleen, anemia or thrombocytopenia (a decrease in the number of platelets, a blood cell that plays a role in blood clotting). During the chronic phase, patients generally respond well to medication.

Accelerated Stage

The accelerated phase is an intermediate stage between the chronic leukemia stage and the aggressive blast phase. Not all people with chronic myeloid leukemia go through the accelerated phase. Some people move directly from chronic leukemia stages to blast crises.

During the accelerated stage, blast cells counts increase and fewer normal blood cells develop. Treatment remains similar to that employed during chronic leukemia stages, but chemotherapy may play a more important role. An accelerated phase typically lasts between three to six months before blast crisis begins.

Blast Crisis Leukemia Stage

The blast crisis represents the final stages of chronic myeloid leukemia. During a blast crisis, the number of blast cells increases dramatically, accumulating to more than 30 percent of total blood cells, according to the University of Maryland’s Greenebaum Cancer Center (2009). At this point, chronic myeloid leukemia resembles acute leukemia.

Symptoms worsen during the blast crisis, and medication becomes less effective. Chronic leukemia cells may metastasize and form tumors in other areas of the body, including the bones, brain, lungs, lymph nodes and skin.

Chronic Myeloid Leukemia Prognosis

Chronic myeloid leukemia prognosis is most positive for people diagnosed in the chronic leukemia stages. People diagnosed during the accelerated or blast leukemia phases generally have a poor prognosis.

Prior to the development of the targeted chemotherapy drug imatinib, the survival rate for chronic myeloid leukemia averaged three to five years after diagnosis. Imatinib improved chronic myeloid leukemia prognosis dramatically. Patients who receive imitinib as an initial therapy for CML have a five-year survival rate of 95 percent, according to a study published in the “New England Journal of Medicine” (2006). Advances in stem cell transplantation have also improved chronic myeloid leukemia prognosis.


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Druker, B., Guilhot, F., O’Brien, S., Gathmann, I., Kantarjian, H, … Larson, R. (2006). Five-year follow-up of patients receiving imatinib for chronic myeloid leukemia. Retrieved September 28, 2010, from http://www.nejm.org/doi/full/10.1056/NEJMoa062867 – t=articleDiscussion.

U.S. Library of Medicine. (2010). Chronic myelogenous leukemia. (CML). Retrieved September 23, 2010, from http://www.nlm.nih.gov/medlineplus/ency/article/000570.htm.

University of Maryland Marlene and Stewart Greenebaum Cancer Center. (2009). Chronic myelogenous leukemia. Retrieved September 23, 2010, from http://www.umgcc.org/hem_malig_program/chron_myel-stages.htm.