Chronic myeloid leukemia (CML) is a cancer of blood forming cells in the bone marrow. Abnormal cells gradually fill the bone marrow and spill into the bloodstream. The disease usually develops slowly and symptoms such as anemia, bleeding problems or infection may not occur for years after the disease begins. The treatment aims to reduce the number of abnormal cells.
On this page
- What is leukemia?
- What is normal blood made up of?
- The bone marrow, stem cells and cell production
- The main types of leukemia are:
- What is chronic myeloid leukemia?
- Who gets chronic myeloid leukemia?
- What causes chronic myeloid leukemia?
- How to develop chronic myeloid leukemia and what are the symptoms?
- How is chronic myeloid leukemia diagnosed?
- What is the treatment for chronic myeloid leukemia?
- What is the outlook (prognosis)?
- More help and information
What is leukemia?
Leukemia is a cancer of the bone marrow cells (the cells that become blood cells). Cancer is a disease of the cells in the body. Many cancers arise from the different cell types. What all cancers have in common is that the cancer cells are abnormal and do not respond to normal control mechanisms. A large number of cancer cells because they multiply accumulate 'uncontrolled', or because they live considerably longer than normal cells, or both.
With leukemia, the cancer cells in the bone marrow spill into the bloodstream. There are several types of leukemia. Most types of cells which arise normally develop in the white blood cells. (The word leukemia comes from a Greek word meaning "white blood".) If you develop leukemia is important to know exactly what type. This is because the outlook (prognosis) and treatments vary for different types. Before discussing the different types of leukemia that can help to know some basics about normal blood cells and how they are made.
What is normal blood made up of?
- The blood cells, which can be seen under a microscope, constituting about 40% of blood volume. Blood cells are divided into three main types:
- Red blood cells (erythrocytes). This makes the blood red. One drop of blood contains about five million red cells. Red blood cells contain a chemical called hemoglobin. This binds to oxygen and carries oxygen from the lungs to all body parts.
- White blood cells (leukocytes). There are different types of white blood cells called neutrophils (polymorphs), lymphocytes, eosinophils, monocytes and basophils. They are part of the immune system. Its main function is to defend the body against infections.
- Platelets. These are small cells and help blood clotting if we cut.
- Plasma is the liquid portion of blood and accounts for approximately 60% of blood volume. The plasma is composed mainly of water but contains many different proteins and other chemicals, such as hormones, antibodies, enzymes, glucose, fat particles, salts, etc.
When blood is poured out of the body (or a blood sample is taken in a plane glass tube) and plasma cells certain group of proteins to form a coagulum. The remaining clear fluid called serum.
The bone marrow, stem cells and cell production
Blood cells are produced in the bone marrow cells "mother". Bone marrow is the soft "fluffy" material in the center of bones. The large, flat bones such as the pelvis and breastbone (sternum), bone marrow contain more. To make blood cells constantly needing a transplant of healthy bone marrow and nutrients from your diet, including iron and some vitamins.
Stem cells are primitive (immature) cells. There are two major types of bone marrow – myeloid and lymphoid stem cells. These derive from even the most common primitive pluripotent stem cells. Stem cells continually divide and produce new cells. Some new cells remain as stem cells and others go through a series of maturation stages ('precursor' cells or 'Blast') before forming into mature blood cells. Mature blood cells are released from the bone marrow into the blood.
- White blood lymphocytes develop from lymphoid stem cells. There are three types of mature lymphocytes:
- B lymphocytes produce antibodies that attack bacteria infecting viruses, etc.
- T cells help B cells to produce antibodies.
- Natural killer cells that help protect against infection.
- All other different blood cells (red cells, platelets, neutrophils, basophils, eosinophils and monocytes) develop from myeloid stem cells.
You make millions of blood cells every day. Each cell type has an expected lifetime. For example, RBCs normally lasts about 120 days. Some white blood cells made just hours or days – some last longer. Every day, millions of blood cells die and decompose at the end of its useful life. Normally there is a balance between the number of blood cells that you do, and the number who die and decompose. Several factors contribute to maintaining this balance. For example, certain hormones in the bloodstream and chemicals in the bone marrow, called "growth factors", help regulate the number of blood cells are made.
The main types of leukemia are:
- Acute lymphoblastic leukemia (ALL).
- Chronic lymphocytic leukemia (CLL).
- Acute myeloid leukemia (AML).
- Chronic myeloid leukemia (CML).
There are several subtypes "" of each. In addition, there are some other rare types of leukemia.
- "Acute" means the disease develops and progresses rapidly.
- 'Chronic' means persistent or permanent. When it comes to chronic leukemia word also means the disease develops and progresses slowly (even without treatment).
- "Lymphoblastic" and "lymphocytic" means that a cancer cell is an abnormal cell that originated from a lymphoid stem cell.
- "Myeloid" means that a cancer cell is an abnormal cell that originated from a myeloid stem cell.
The rest of this leaflet is only about CML. There are other separate leaflets called leukemia – an overview, lymphoblastic leukemia, acute myeloid leukemia, acute and chronic lymphocytic leukemia.
What is chronic myeloid leukemia?
CML is sometimes called chronic myeloid leukemia, chronic granulocytic leukemia myelocytic leukemia, or chronic.
CML develops due to a problem with a stem cell in the bone marrow, which becomes abnormal. The stem cell and multiplies abnormal cells are made from stem cells to mature and become abnormal almost normal white blood cells – especially neutrophils, basophils and eosinophils (collectively referred to as granulocytes). A large number of these cells in the bone marrow and are poured into the bloodstream.
(In contrast, in acute myeloid leukemia (AML), the abnormal cells that are produced in large quantities are abnormal immature "blasts." This is a different disease CML. (The AML separate booklet provides further details. )
Typically, CML develops and progresses slowly – over months or years, even without treatment.
Who gets chronic myeloid leukemia?
CML is the rarest of the four main types of leukemia. There are some 750 cases in the UK every year. It occurs mostly in adults and becomes more common with age. The mean age at diagnosis is 50 years. It is very rare in children. It is more common in men than in women.
What causes chronic myeloid leukemia?
A leukemia is thought to initiate the first of an abnormal cell. What seems to happen is that certain vital genes which control how the cell divides, multiplies and dies, damaged or altered. This causes the abnormal cell. If abnormal cell survives can multiply and produce many abnormal cells develop into leukemia. In the case of CML, is a blood stem cell that is damaged and affected first.
In most cases of CML, the reason why a stem cell becomes abnormal is not known. Research has shown that exposure to electromagnetic fields and living near power lines does not increase the risk for chronic myeloid leukemia. There are certain risk factors "that increase the likelihood that they will develop leukemia, but these represent only a small number of cases. Known risk factors for CML are high doses of radiation (eg, previous radiotherapy for another condition ) and exposure to the chemical benzene.
CML is not a hereditary disease and does not run in families.
How to develop chronic myeloid leukemia and what are the symptoms?
Usually, CML is a three phases:
An initial chronic phase
This phase usually lasts for a number of years (often five years or more). During this phase of the disease progresses very slowly. You can remain stable, with little or no change in the severity of the disease for prolonged periods. Many people at this stage have no symptoms or mild symptoms. CML can be diagnosed for the first time by chance at this stage that a blood test is taken for another reason.
The average time for this phase is 4-5 years. However, in some people this phase can last over 20 years.
In the chronic phase are 5% or less number of blast cells in blood and bone marrow.
A phase transformation (also known as the accelerated phase)
Over time, the disease process tends to accelerate and change. At this stage, the number of abnormal cells in the bone marrow and blood accumulates. Many of the abnormal cells are 'explosion' (immature) of white blood cells. In this phase there are 6-30% blast cells in blood and bone marrow. As many abnormal cells accumulate in the bone marrow is difficult to normal cells of the bone marrow sufficient for survival and normal cells. Therefore, the main problems and symptoms tend to develop include:
- Anemia. This occurs as the number of red cells in the blood decreases. This can cause fatigue, shortness of breath and other symptoms. You can also look pale.
- Problems blood clotting. This is due to the low number of platelets in the bloodstream. This can cause bruising, bleeding gums and other problems related to bleeding.
- Severe infections. Abnormal cells and white blood blast cells do not protect against infection. If there are a limited number of normal white blood cells that fight infection generally, the risk of developing serious infections.
Other symptoms may include: mild pain on the left side of the abdomen caused by inflammation of the spleen (the spleen can become enlarged with abnormal cells), sweating and weight loss.
The transformation phase typically lasts 6-24 months before moving on to the third phase explosion. Sometimes the chronic phase goes directly to the burst phase without intermediate processing stage.
'Explosion' A third phase
At this stage, the condition worsens rapidly and behaves as an acute leukemia. Many immature cells 'Blast' develop and fill much of the bone marrow and cause worsening of the symptoms described above. Many blast cells spill into the bloodstream and the blast count of cells in blood is high. At this stage, no more than 30% blast cells in blood and bone marrow.
Rarely, CML becomes a condition called myelofibrosis. This means that the bone marrow can not produce red blood cells, white cells and platelets because it is replaced by scar tissue (fibrosis).
How is chronic myeloid leukemia diagnosed?
A blood test typically shows changes in the number and pattern of the white blood cells. This suggests the diagnosis of CML. A bone marrow sample is performed to confirm the diagnosis. In the accelerated phase and blast, the number of blast cells in the blood sample ("number of blast cells') also increases.
A bone marrow sample
For this test, a needle is inserted into the pelvic bone (or sometimes the breastbone (sternum)). Local anesthesia is used to numb the area. A small amount of bone is removed using a syringe. Sometimes, a small core of marrow also have (trephine biopsy). The samples were placed under the microscope for abnormal cells and proved otherwise. See separate leaflet called bone marrow biopsy and aspiration for details.
Cellular and genetic testing
Detailed tests are performed on abnormal cells obtained from the sample of blood or bone marrow. The chromosomes of the cells within certain changes are observed. Chromosomes are the parts of the cell containing DNA – the genetic makeup of the cell.
In most cases of CML abnormal cells contain an altered chromosome 22. This shortens changed chromosome and is called the "Philadelphia chromosome. An abnormal gene called BCR-ABL is done in the normal chromosome 22. This gene is likely to be responsible for the abnormal behavior of each cell cancerous abnormal. (These chromosomal changes only occur in leukemia cells and not normal cells of the body.) Some less common subtypes CML not have the Philadelphia chromosome.
Several other tests
A chest x-ray, blood tests and other tests may be done to assess their general welfare.
What is the treatment for chronic myeloid leukemia?
The treatment of the initial chronic phase
The goal of treatment is to control the process of the disease, relieve symptoms and prevent (or delay) in the progression of the other two stages.
You may be advised to have one or more of the following treatments:
- Imatinib (Glivec ®) tablets. This drug is known as a "tyrosine kinase inhibitor. Chemistry tyrosine kinase is performed by the abnormal BCR-ABL gene on chromosome of the 'Philadelphia' described above. It is believed to be responsible for the abnormal growth and Abnormal cell behavior. Imatinib acts by blocking the effect of tyrosine kinase.
- Interferon alpha. This medicine has been shown to help the immune system fight against leukemia cells. Interferon alfa is sometimes given, but now imatinib is given much more often.
- Tablets chemotherapy. Chemotherapy is a treatment that uses anticancer drugs to kill cancer cells or prevent them from multiplying. (See separate leaflet called chemotherapy with cytotoxic drugs for details.) Another drug called arabinoside is also sometimes used to treat CML.
- A stem cell transplant (SCT) – sometimes called bone marrow transplant – is sometimes an option in younger patients with CML. This can be curative. (See separate leaflet called stem cell transplantation for details.)
The processing and treatment phases of ovens
Treatment is usually with more intensive chemotherapy given for the chronic phase. This usually means a combination of chemotherapy drugs administered directly into a vein (intravenous chemotherapy). Imatinib (Glivec ®) tablets may also be used.
Other treatments include antibiotics or antifungal drugs if infection occurs, blood and platelet transfusions to improve low levels of red blood cells and / or platelets.
What is the outlook (prognosis)?
In general, the prognosis is quite good. The treatment in most cases but not curative treatment often keeps under control the disease for a number of years. A successful SCT people with this treatment is the only way to a permanent cure.
Treatment of cancer and leukemia is a development area of medicine. New treatments continue to be developed and the information on outlook above is very general. As mentioned above, there are some newer drugs that have been introduced in recent years that show promise to improve the outlook. The specialist who knows your case can give more accurate information about the prospects for your particular situation.
More help and information
Macmillan Cancer Support
Tel (Helpline): 0808 808 0000 Web: www.macmillan.org.uk
Provides information and support to anyone affected by cancer and leukemia.
Web: http://cancerhelp.cancerresearchuk.org/ ~ ~ V ~ ~ aux provides data on cancer, including treatment options.
Leukemia Research Fund
Mainly engaged in research and raises funds for these purposes. Their website includes a wide range of information on leukemia patients.
A website based support group, published and maintained by CML patients and caregivers
Tel: 08088 010 444 Web: www.leukaemiacare.org.uk
It aims to promote the welfare of people with leukemia, blood disorders and their allies.
Other support groups
View www.patient.co.uk / selfhelp.asp for a list of self-help and support groups for patients with cancer and leukemia.