Leukaemia

Leukaemia is a cancer of blood cells arising in the bone marrow. Healthy blood consists of many cell types that work together in a balanced system.

In leukaemia, one type of blood cell is abnormal and builds up in numbers. This deprives other cells of the space and nutrients to function properly. Leukaemia develops in the bone marrow, where blood cells are formed. Leukaemic cells can overwhelm normal blood cell formation.

Leukaemic cells can also spread around the body, disrupting the function of other organs.

There are many types of leukaemia. The names of leukaemias can describe features of the disease and its origins. Many leukaemias’ names reflect the normal blood cell types that the leukaemic cells are closest to:

• Lymphoblastic (or lymphocytic) leukaemias resemble immune cells called lymphocytes.
• Myeloid (or myelogenous) leukaemias can have features of ‘myeloid’ immune cells such as neutrophils, or the early developmental stages of red blood cells or platelets.

Leukaemias are often further described by how rapidly the diseased cells are accumulating and worsening the disease.

• Acute leukaemias involve rapidly dividing cells that have features of immature (undeveloped) blood cells. These cells can quickly hinder normal blood cell functions such as fighting infection.
• Chronic leukaemias display a slow accumulation of cancerous cells that resemble more mature blood cells. This can occur over months or years.

In some cases, a leukaemia may begin in a chronic phase but later change, or progress, to an acute leukaemia.

Some leukaemias are very similar to other cancers of blood cells including:

• Lymphoma
• Myeloma
• Myeloproliferative disorders

Blood cells develop from stem cells in the bone marrow. During development, immature cells divide and change the proteins that they produce, gradually becoming more like the mature cell.

Many genetic changes have been discovered that make a cell become leukaemic. Many of these changes are in genes that have a function in normal blood development. Genetic changes that contribute to leukaemia often prevent a developing blood cell from maturing.

Most cases of leukaemia arise ‘spontaneously’. Occasionally people in a family may share genes that make them more likely to develop leukaemia.

Some factors increase a person’s risk of developing leukaemia. These include:

• Exposure to agents that damage DNA, such as radiation or tobacco smoke.
• Treatment with immune-suppressing medications.
• Genetic disorders, such as Down syndrome.
• Certain blood disorders, such as myelodysplastic syndrome, that can precede leukaemia.

The risk of an adult developing leukaemia increases with age. However, there are certain types of acute leukaemia that are much more common in children.

Different leukaemia types respond to different treatments. Medical research has led to treatments that can cure some types of leukaemia, particularly childhood leukaemias. For some types of leukaemia, treatments may not completely eliminate the leukaemic cells, but contained them for many years. This allows the patient to live in relatively good health.

Common leukaemia treatments include:

• Chemotherapy uses medications that damage DNA and kill dividing cells.
• Radiotherapy uses radiation to kill rapidly dividing cells.

Blood stem cell transplantation is an important part of leukaemia treatment. A person with leukaemia can receive very strong chemotherapy and radiotherapy to purge leukaemic cells from their body. As well as killing the leukaemic cells, this also kills the person’s normal blood forming cells. This stops the production of new blood cells. This can be restored by a blood stem cell transplant. The blood stem cells may be from the patient themself, or from another person.

Many gene changes have been discovered that contribute to leukaemia. Often these alter the amounts of the proteins that normally regulate cell proliferation and longevity. Treatments that stop these proteins from functioning are showing promise in treating leukaemia.

Some gene changes found in leukaemia result in new proteins being formed, often from rearranged genes. These new, leukaemia-promoting proteins are attractive targets for treatment, as they are unique to leukaemia cells. This means that medications that specifically block the function of the new protein should not have any effects on normal cells.

You can read more about targeted therapies on our medicinal chemistry page

The Leukaemia Foundation provides information and support for people living with leukaemia.

WEHI researchers are not able to provide specific medical advice specific to individuals. If you have cancer and wish to find out more information about clinical trials, please visit the Australian Cancer Trials or the Australian New Zealand Clinical Trials Registry, or consult your medical specialist.