Definition Chronic myelogenous leukaemia (CML) is a kind of cancer that occurs in a specialised white blood cell called a myelocyte. The cancerous change occurs in the bone marrow where all blood cells are made. CML develops slowly over several years.
What is going on in the body? All blood cells develop in the bone marrow. Each type of blood cell has a specific function. Normal white cells help fight infection. Red blood cells carry oxygen. Platelets help clot the blood when there is an injury.
CML occurs when a specialised white cell, called a myelocyte, undergoes a cancerous change. When these cancerous cells begin to grow in the bone marrow, normal bloods cells are destroyed or crowded out. In CML, this occurs over a long period. It can take years for the bone marrow to be severely affected. Problems with the bone marrow can lead to the following:
fewer normal white cells, so the person develops infections easily. The infections may be serious as well as life-threatening.
fewer platelets, so that the person bruises or bleeds easily
anaemia, or low numbers of red blood cells, which makes the person weaken and tire easily
CML cells eventually leave the bone marrow and travel throughout the body in the bloodstream. So many CML cells may enter the bloodstream that the blood becomes too thick. The number of CML cells may be as many as a 150 times the normal amount of white cells. However, these CML cells do not function like normal white cells.
The early part of the disease, when it is causing few problems, is called the chronic phase. Eventually, CML cells will begin multiplying very rapidly. At that time, the disease will be similar to acute non-lymphatic leukaemia. CML is said to be in terminal phase (also known as a blast crisis) because there are so many immature white cells in the body. At that point the disease is difficult to treat and may lead to death. This may happen several months or years after the disease is diagnosed.
What are the signs and symptoms of the disease? There may be no symptoms. CML is found when a routine blood sample is checked.
The most common symptom is severe fatigue. The person may also have unexplained weight loss and night sweats.
Occasionally, the person can feel pain in the upper left side of the abdomen due to a swollen spleen.
What are the causes and risks of the disease? The cause of CML is unknown.
What can be done to prevent the disease? Nothing can be done to prevent CML.
How is the disease diagnosed? CML is diagnosed by examining a blood sample. Genetic studies may be done on the blood sample as well. This helps to identify any special characteristics of the leukaemia, which will help doctors treat it. A sample of bone marrow will be removed and examined as well, in a procedure known as bone marrow biopsy.
What are the long-term effects of the disease? If CML is not treated effectively, it eventually causes death. Sometimes persons with CML can be free of disease for many years.
What are the risks to others? There are no risks to others. Cancer does not spread from person to person.
What are the treatments for the disease? During the chronic phase, which may last for years, treatment includes the following:
Chemotherapy with medications such as hydroxyurea or bulsulfan may decrease the numbers of CML cells for many years.
Interferon, a natural substance produced by white cells, may also help the body control the CML cells. Known as a biological response modifier, interferon does not cure the cancer. It can only control it for a period of time.
Some people are given the bone marrow from another person to help recovery. This is called a bone marrow transplant. A bone marrow transplant during this phase may cure the person. This therapy is very intense and may not be right for every person that has CML.
During the terminal phase, CML will be treated like acute leukaemia.
If the cancerous cells can be destroyed, which is a stage known as remission, the person may be considered for a bone marrow transplant.
Remission is usually followed by additional therapy.
What are the side effects of the treatments? The side effects depend on the treatment.
Chemotherapy medications given during the chronic phase cause only mild side effects. Mild nausea will usually pass with time. The medications given during the terminal phase cause many side effects.
Interferon is given by daily injection. It can cause long-term flu-like symptoms.
The effects of bone marrow transplantation are severe and life-threatening. The person will be in a facility that specialises in bone marrow transplants. Intensive care will be given to manage any side effects and problems.
What happens after treatment for the disease? The person with CML will need to be followed closely for signs of the disease worsening. Persons who have had a bone marrow transplant will need lifelong follow-up even if the disease is in remission.
How is the disease monitored? During the chronic phase, blood samples will be monitored closely for signs that the CML is not under control. When this happens, a bone marrow biopsy will be done. If the person is in a remission, blood samples will again be monitored closely. Bone marrow biopsies will also be done, if necessary.
Author: Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 23/09/2004 Contributors Potential conflict of interest information for reviewers available on request
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