Your blood is made up of red cells, white cells and platelets (cells to help your blood clot). Under normal conditions these cells are produced in your bone marrow. They all develop from a small number of healthy immature blood cells, 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 and move out of the bone marrow into the blood. As the cancerous cells grow quickly within the bone marrow, they can overcrowd the space. This disrupts the production of normal blood cells which leads to anaemia and increases the risk of infection.
There are several different types and subtypes of leukaemia. It can be either acute or chronic. The terms ‘acute’ and ‘chronic’ refer to how quickly the disease develops and progresses.
Leukaemia is also typed by the cell line that has turned cancerous, either from a myeloid cell or a lymphoid cell. Myeloid leukaemia starts in cells that would normally develop into red blood cells, platelets and neutrophils. Lymphocytic leukaemia starts in cells that would normally become white blood cells, called lymphocytes, which are part of your immune system.
There are 4 main types of leukaemia
Acute leukaemia
Acute leukaemia develops and progresses quickly and therefore needs to be treated as soon as it's diagnosed. It acts on very immature blood cells, preventing them from maturing properly. Most people will only have had acute leukaemia for a few weeks before being diagnosed.
Acute myeloid leukaemia is more common in adults and more common in the elderly. Various treatments are available for this condition including bone marrow transplant. Read more about acute myeloid leukaemia(external link).
Acute lymphoblastic leukaemia is the commonest type of leukaemia seen in children. There's good treatment available for this type of leukaemia and many children can be cured. When adults get this condition it can be far more serious and very intensive treatment is necessary. Read more about acute lymphoblastic leukaemia(external link).
Video: What is Leukemia?
The following video explains what leukaemia is. Note that the treatment information doesn't apply to all types of leukaemia.
(Cincinnati Children's, US, 2017)
Chronic leukaemia
Chronic myeloid leukaemia is a type of leukaemia caused by damage to a specific chromosome in the nucleus of the developing white blood cells. It develops over several months. It can occur at any age, but is more common in adults and is rarely seen in children. Treatment is available which can more or less eradicate (get rid of) the disease. People with this condition can usually lead a normal life with treatment. Read more about chronic myeloid leukaemia(external link).
Chronic lymphocytic leukaemia is a type of leukaemia that can develop over many years. Some people with this condition have no symptoms and it's only picked up on a blood test. Often it doesn't require treatment. However for some people it can progress more rapidly and cause symptoms, and chemotherapy may be needed to control its progress. People with chronic lymphocytic leukaemia have a poor immune system and have a high risk of developing infections. Read more about chronic lymphocytic leukaemia(external link).
The cause of leukaemia isn't completely understood. In many cases it's possible to find abnormalities of the chromosomes in the cells in the bone marrow in people with leukaemia, but in most cases the cause of these changes remains unknown.
Some factors have been suggested as possible causes including, radiation, exposure to chemicals, and various viruses, but a definite link has only been shown in a few instances.
General symptoms
The symptoms of leukaemia are usually due to a shortage of red cells, white cells or platelets.
Red blood cell shortage (low haemoglobin or anaemia) may lead to fatigue, breathlessness, dizziness and pale skin colouring.
Insufficient or ineffective white blood cells (neutropenia or lymphocytosis) may lead to repeated or serious infections.
A decrease in the number of platelets (thrombocytopenia) may lead to:
increased bleeding and bruising in the skin
nosebleeds
heavy menstrual bleeding
rectal bleeding (bleeding from your bottom).
Specific symptoms for some types of leukaemia
Chronic myeloid leukaemia can cause a large spleen leading to some left sided abdominal discomfort.
People with chronic lymphoid leukaemia often have enlarged lymph nodes. These can cause swelling in your neck and under your arms. You can also develop sweating at night and lose weight.
However, the symptoms of leukaemia are typical of many other diseases and, in some types of leukaemia, there's 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
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, bone marrow cell typing and genetic studies. Your healthcare provider should be able to give you more information on these results should you wish to discuss or understand them better.
The main aim of treatment is to get rid of the abnormal malignant cells, allowing the normal cells to re-populate the bone marrow. The kind of treatment you would have varies depending on the type of leukaemia you've been diagnosed with.
