Leukaemia

What is leukaemia?

One of the key factors contributing to leukaemia is the production of immature blood cells, which gather in the body and chase out their healthy counterparts.

As the disease progresses, these leukaemia cells accumulate in the bone marrow, replacing, or crowding out, normal white and red blood cells and platelets. The abnormal cells are eventually released into the circulating blood and carried throughout the body. This means the remaining red blood cells cannot transport as much oxygen to the body's tissues and organs, the normal white blood cells cannot fight infection effectively, while the platelets cannot control bleeding effectively.

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, and a decrease in the number of platelets may lead to red skin blotches, bruising, nosebleeds and other bleeding.

The four most common types of leukaemia are:
* Acute lymphoblastic leukaemia (ALL)
* Chronic lymphocytic leukaemia (CLL)
* Acute myeloid leukaemia (AML)
* Chronic myeloid leukaemia (CML)

Acute leukaemia affects cells very early on in their life, causing them to malfunction. Often people with this form of the disease experience infections, bleeding and anaemia and they usually require immediate treatment.

Chronic leukaemia affects more mature cells. Immediate treatment is not always required and, in some cases, might never be necessary.

Leukaemias are categorised as either myeloid or lymphoid.

When leukaemia affects the cells which should eventually develop into platelets, red blood cells, granulocytes and monocytes it is called myeloid, myelocytic, myelogenous or granulocytic leukaemia.

When leukaemia affects the cells destined to become lymphocytes it is called lymphoblastic, lymphoid, lymphocytic, or lymphatic leukaemia.

Causes

The cause of leukaemia is not known for definite, but there are several factors which seem to affect its development. However, these account for only a small number of leukaemia cases. In most other 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 e.g. atomic bomb victims, or people who 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 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.

Diagnosis

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 and 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. The bone marrow is analysed using a wide variety of tests including microscopic analysis and bone marrow culture studies. Diagnosis is generally based on observations from both of these tests.

Treatment

The various forms of leukaemia do not always require treatment, which is particularly the case in the elderly. The main aim of treatment, which varies depending on the type of leukaemia diagnosed, is to eradicate the abnormal malignant cells, allowing the normal cells to re-populate the bone marrow.

Additional information on 'treatment' options can be found under the different forms of leukaemia listed on this website.

For more information on leukaemia, or a copy of our information booklets on the different types of leukaemia, please contact us at lbf@leukaemia.org.nz or 0800 15 10 15.