What is Leukaemia?
Leukaemia is a cancer of cells in the bone marrow (the cells which develop into blood cells). Cancer is a disease of the cells in the body. There are many types of cancer which arise from different types of cell. What all cancers have in common is that the cancer cells are abnormal and do not respond to normal control mechanisms. Large numbers of cancer cells build up because they multiply 'out of control', or because they live much longer than normal cells, or both.
With leukaemia, the cancerous cells in the bone marrow spill out into the bloodstream. There are several types of leukaemia. Most types arise from cells which normally develop into white blood cells. (The word leukaemia comes from a greek work which means 'white blood'.) If you develop leukaemia it is important to know exactly what type it is. This is because the outlook (prognosis) and treatments vary for the different types. Before discussing the different types of leukaemia it may help to know some basics about normal blood cells and how they are made.
The bone marrow, stem cells and blood cell production
Blood cells are made in the bone marrow by 'stem' cells. The bone marrow is the soft 'spongy' material in the centre of bones. The large flat bones such as the pelvis (Hip bone) and breast-bone (sternum) contain the most bone marrow. To constantly make blood cells you need a healthy bone marrow. You also need nutrients from your diet including iron and certain vitamins.
You make millions of blood cells every day. Each type of cell has an expected life-span. For example, red blood cells normally last about 120 days. Some white blood cells last just hours or days - some last longer. Every day millions of blood cells die and are broken down at the end of their life-span. There is normally a fine balance between the number of blood cells that you make, and the number that die and are broken down. Various factors help to maintain this balance. For example, certain hormones in the bloodstream and chemicals in the bone marrow called 'growth factors' help to regulate the number of blood cells that are made.
The main types of leukaemia are:
• Acute lymphoblastic leukaemia - 'ALL' (sometimes called acute lymphocytic leukemia).
• Chronic lymphocytic leukaemia - 'CLL'.
• Acute myeloid leukaemia - 'AML'.
• Chronic myeloid leukaemia - 'CML'.
What is acute myeloid leukaemia?
Acute myeloid leukaemia (AML) is a condition where the bone marrow makes large numbers of abnormal immature white blood cells which are derived from a myeloid stem cell. The abnormal immature cells are called blasts
There are various sub-types of AML, depending on exactly what cell type becomes cancerous and at what stage in the maturing process. Typically, AML develops quite quickly (acutely) and rapidly becomes worse (over a few weeks or so) unless treated
What is the cause for AML?
A leukaemia is thought to first start from one abnormal cell. What seems to happen is that certain vital genes which control how cells divide, multiply, and die are damaged or altered. This makes the cell abnormal. If the abnormal cell survives it may multiply 'out of control' and develop into a leukaemia.
Risk factors include:
• Radiation. For example, previous radiotherapy for another condition. Many survivors of the atom bomb used in world war II developed AML caused by the fall out of radiation.
• Past treatment with chemotherapy or other drugs that weaken the immune system.
• Smoking. (A chemical called benzene in cigarettes is thought to be a risk factor for AML.)
• If you have certain conditions of the bone marrow you have an increased risk of developing AML at a later time. These are called myelodysplastic syndromes and myeloproliferative disorders. For example, thrombocythaemia, polycythaemia rubra vera, myelofibrosis, etc.
What are the main symptoms of AML?
As large numbers of abnormal blast cells are made, much of the bone marrow fills with these abnormal cells. Because of this it is difficult for normal cells in the bone marrow to survive and make enough normal blood cells. Also, the abnormal cells spill out into the bloodstream. Therefore, the main problems which can develop include:
This occurs as the number of red blood cells goes down. This can cause tiredness, breathlessness and other symptoms. You look also look pale.
This is due to low levels of platelets. This can cause easy bruising, bleeding from the gums, and other bleeding-related problems.
• Serious infections:
There is a reduced number of normal white blood cells which usually combat infection. Therefore, serious infections are more likely to develop. The symptoms can vary greatly, depending on the type and site of infection.
The abnormal blasts may also accumulate in other sites. You may therefore develop swollen glands, an enlarged spleen or liver, and occassionally other rare symptoms. Other common symptoms include pain in the bones or joints, persistent fever, and weight loss. Left untreated, AML usually causes death within a few months.
How is AML diagnosed?
A blood test
A blood test can often suggest the diagnosis of AML. The test will typically show a low number of: red blood cells, normal white blood cells, and platelets. Some blast cells which have spilled into the bloodstream from the marrow are also usually seen. Sometimes large numbers of blast cells occur in the bloodstream. Further tests are usually done to confirm the diagnosis.
A bone marrow sample
For this test a small amount of bone marrow is removed by inserting a needle into the pelvis bone (or sometimes the breastbone (sternum)). Local anaesthetic is used to numb the area. A small sample of bone may also be taken. The samples are put under the microscope to look for abnormal cells, and tested in other ways. This can confirm the diagnosis.
Cell and chromosome analysis
Detailed tests are done on abnormal blast cells obtained from the bone marrow sample or blood test. The chromosomes within the cells are checked for certain changes. Chromosomes are the parts in the cell which contain DNA - the genetic make-up of the cell. Various sub-types of AML can be diagnosed by detecting changes which occur to parts of one or more chromosome. (These chromosome changes only occur in the leukaemia cells, not the normal body cells.) It is important to know the exact sub-type of AML as the treatments and outlook (prognosis) can vary, depending on the type.
How is AML treated ?
The aim of treatment is to kill all the abnormal cells. This then allows the bone marrow to function normally again, and produce normal blood cells. The main treatment is chemotherapy. A stem cell transplant is used in some cases.
The exact treatment regime used in each case (the drugs used, doses, length of treatment, etc) takes into account various factors which include the age, sex and general health. It also depends on how the disease responds to the first course of treatment and the exact sub-type of AML.
On the basis of these factors, people with AML are classed as 'low', 'standard' or 'high' risk. The type and intensity of treatment given can depend on your risk classification. For example, more intensive treatment is usually offered if your risk is 'high'.
Chemotherapy is a treatment which uses anti-cancer drugs to kill cancer cells, or to stop them from multiplying. As many drugs are likely to be given straight into a vein (intravenous) over a prolonged period, it is usual for a plastic tube to be put into a large blood vessel and left for the duration of treatment. This enables drugs to be injected or 'dripped' into the large vein via the plastic tube without the need for repeated needle pricks.
Usually the course of chemotherapy is given in 'cycles'. A cycle is a spell of treatment followed by a rest from treatment. For AML each cycle typically consists of 5-10 days of treatment followed by 3-4 weeks rest. The rest from treatment allows your body to recover from any side-effects, and gives a chance for damaged normal cells to recover before the next spell of treatment.
The length of a full course of treatment is often about six months. So this may consist of about 4-6 cycles of treatment over the six months. But a full course of treatment can vary depending on your circumstances.
Bone Marrow transplant
Bone marrow transplant is sometimes used, depending on the type of the AML. For example, it may be used in types classed as 'high risk', and in some cases where the leukaemia has recurred (relapsed) following treatment with usual chemotherapy.
Other treatments include: antibiotics or antifungal drugs if infection occurs; blood transfusions to counter low levels of red blood cells and platelets; to control nausea and vomitimg during chemotherapy.
Treatment of relapses
Despite treatment, in some cases the AML returns (relapses) sometime after treatment ends. Relapses are treated in a similar way to the initial treatment, but the treatment regime is often more intensive and may include a stem cell transplant.
What is the outlook?
The outlook for AML has considerably improved over the years and continues to improve. It is difficult to give exact figures. However, the chance of a good response to treatment varies. It depends on factors such as the exact type of the AML and your age.
We will explain you in detail the outlook when we start the treatment.