Leukaemia is the general name given to a group of blood-related cancers that develop in the bone marrow.
Under normal conditions your bone marrow contains a small number of healthy immature blood cells, sometimes called blast cells. These immature blood cells mature and develop into red cells, white cells and platelets, which are eventually released into the blood stream.
Leukaemia begins in developing blood cells, which have undergone a malignant (cancerous) change. Instead of maturing properly, these cells grow and multiply in an uncontrolled fashion, disrupting the normal blood cell production and function before travelling from the bone marrow to circulate through the blood.
There are several different types and subtypes of leukaemia.
Leukaemia can be either acute or chronic. The terms ‘acute’ and ‘chronic’ refer to how quickly the disease develops and progresses.
- Acute leukaemia develops and progresses quickly and therefore needs to be treated as soon as it is diagnosed. It affects very immature blood cells, preventing them from maturing properly.
- In chronic leukaemia a there is an accumulation of more mature but abnormal white cells. It can occur at any age, but is more common in older adults and is rarely seen in children.
Leukaemia can also be either myeloid or lymphoid. The terms myeloid and lymphoid refer to the types of cell in which the leukaemia first started.
- Myeloid: When leukaemia starts in cells which should eventually develop into platelets, red blood cells, granulocytes and monocytes, it is called 'myeloid', 'myelocytic', 'myelogenous' or 'granulocytic' leukaemia.
- Lympohoid: When leukaemia starts in cells destined to become lymphocytes (white blood cells), it is called 'lymphoblastic', 'lymphoid', 'lymphocytic', or 'lymphatic' leukaemia.
The cause of leukaemia is not completely understood. There are several factors which seem to affect its development. In most instances, the cause of the disease remains unknown. Having one or more of the factors mentioned below does not mean that you will definitely develop leukaemia. If you are concerned about any of these you should talk to your doctor.
Genetic factors: Children with Down's syndrome have an increased risk of developing acute leukaemia, as do children with some other rare chromosomal abnormalities. Genetic factors rarely play a role in the development of chronic leukaemia.
Radiation: Leukaemia occurs at higher than average rates among people exposed to intense radiation, eg. atomic bomb victims, or people who have received radiation therapy for the treatment of other diseases in the past.
Chemicals: Workers exposed to benzene have an increased risk of developing acute leukaemia. Some types of cytotoxic (toxic to cells) drugs used in organ transplant patients and cancer treatments also increase the risk of developing leukaemia.
Viruses: In certain areas of the world, such as southwest Japan, parts of Africa and the Caribbean, a particular type of leukaemia has been shown to occur in local residents who have been exposed to a virus known as Human T-cell Leukaemia Virus (HTLV). However, only a small number of people who have had this infection eventually develop leukaemia.
Someone with leukaemia may experience many of the symptoms associated with certain types of blood cell shortage. For example:
- red blood cell shortage may lead to fatigue and pale skin colouring
- insufficient or ineffective white blood cells may lead to repeated infections
- a decrease in the number of platelets may lead to red skin blotches, bruising, nosebleeds and other bleeding.
However, the symptoms of leukaemia are typical of many other diseases and, in some types of leukaemia, there is no evidence the disease is present until it reaches an advanced stage.
Leukaemia is diagnosed using either a blood test or a bone marrow test (bone marrow biopsy). When a blood sample is analysed, the number of white blood cells, red blood cells and platelets are counted. The blood count is considered abnormal if any of the following are found: a low platelet count, a low number of red blood cells, a low count of mature white blood cells, or a high number of immature or prematurely released white blood cells, called blasts.
Bone marrow is analysed using a wide variety of tests including microscopic analysis and bone marrow culture studies.
Treatment depends on the individual patient and the type of leukaemia, but can include chemotherapy, radiation treatment and stem cell or bone marrow transplant.
The main aim of treatment, which varies depending on the type of leukaemia diagnosed, is to get rid of the abnormal malignant cells, allowing the normal cells to re-populate the bone marrow.
The four main types of leukaemia are:
Acute myeloid leukaemia (AML) Leukaemia & Blood Cancer NZ
Chronic myeloid leukaemia (CML) Leukaemia & Blood Cancer NZ
Acute lymphoblastic leukaemia (ALL) Leukaemia & Blood Cancer NZ
Chronic lymphocytic leukaemia (CLL) Leukaemia & Bloood Cancer NZ