Chronic myelogenous leukemia (CML) is cancer that starts inside bone marrow. This is the soft tissue in the center of bones that helps form all blood cells.
CML causes an uncontrolled growth of immature cells that make a certain type of white blood cell called myeloid cells. The diseased cells build up in the bone marrow and blood.
Cause of CML is related to an abnormal chromosome called the Philadelphia chromosome.
Radiation exposure can increase the risk of developing CML. Radiation exposure can be from radiation treatments used in the past to treat thyroid cancer or Hodgkin lymphoma or from a nuclear disaster.
It takes many years to develop leukemia from radiation exposure. Most people treated for cancer with radiation do not develop leukemia. Most patients with CML have not been exposed to radiation.
CML most often occurs in middle-age adults and in children.
Chronic myelogenous leukemia is grouped into several phases:
The chronic phase can last for months or years. The disease may have few or no symptoms during this time. Most people are diagnosed during this stage, when they have blood tests done for other reasons.
The accelerated phase is a more dangerous phase. Leukemia cells grow more quickly. Common symptoms include fever (without infection), bone pain, and a swollen spleen.
Untreated CML leads to the blast crisis phase. Bleeding and infection may occur due to bone marrow failure.
Other possible symptoms of a blast crisis include:
A physical examination often reveals a swollen spleen. A complete blood count (CBC) shows an increased number of white blood cells with many immature forms present and an increased number of platelets. These are parts of the blood that help blood clot.
Other tests that may be done include:
Medicines that target the abnormal protein made by the Philadelphia chromosome are usually the first treatment for CML. These medicines can be taken as pills.
Sometimes, chemotherapy is used first to reduce the white blood cell count if it is very high at diagnosis.
The blast crisis phase is very difficult to treat. This is because there is a very high count of immature white blood cells (leukemia cells).
The only known cure for CML is a bone marrow transplant, or stem cell transplant. Most patients, though, do not need a transplant because the targeted medicines are successful. Discuss your options with your oncologist.
You and your healthcare provider may need to manage many other issues or concerns during your leukemia treatment, including:
You can ease the stress of illness by joining a cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.
Taking the targeted medicines have greatly improved the outlook for patients with CML. When the signs and symptoms of CML go away and blood counts and bone marrow biopsy appear normal, the person is considered in remission. Many persons can remain in remission for many years while on this medicine.
Stem cell or bone marrow transplant is usually considered in persons whose disease comes back or gets worse while taking the initial medicines. Transplant may also be recommend for patients who are diagnosed in accelerated phase or blast crisis.
Blast crisis can lead to complications, including infection, bleeding, fatigue, unexplained fever, and kidney problems. Chemotherapy can have serious side effects, depending on the drugs used.
Avoid exposure to radiation when possible.
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.