What is leukaemia?
Bone marrow is soft, “spongy” material in our bones that in healthy people produces a steady supply of new blood cells (including red blood cells that carry oxygen around the body, white blood cells that help fight infection, and platelets that have a role in blood clotting).
In people with leukaemia, the bone marrow produces large numbers of abnormal white blood cells that grow and multiply “out of control”. These abnormal cells may not function properly and may affect the ability of normal blood cells to perform their usual functions.
There are many types of leukaemia, some of which are more common in children, while others are more common in adults. The different types of leukaemia are classified according to how quickly the disease develops and worsens – either chronic (gets worse slowly) or acute (gets worse quickly) – as well as by the type of blood cell affected – lymphoid (lymphocytic) cells or myeloid (myelocytic).
The four most common types of leukaemia are:
- Chronic lymphocytic leukaemia (CLL): occurs mainly in adults and almost never in children.
- Chronic myeloid leukaemia (CML): occurs mainly in adults.
- Acute lymphoblastic leukaemia (ALL): occurs more commonly in children but also affects adults.
- Acute myeloid leukaemia (AML): occurs in both adults and children.
The precise cause of leukaemia is not known. However, some risk factors that increase the likelihood of developing leukaemia have been identified. The risk factors, which differ for different types of leukaemia, include the following:
- Radiation: exposure to very high levels of radiation increases the risk of acute myeloid leukaemia, chronic myeloid leukaemia, and acute lymphocytic leukaemia
- Smoking: cigarette smoking increases the risk of acute myeloid leukaemia
- Benzene: exposure to benzene can lead to the development of acute myeloid leukaemia, chronic myeloid leukaemia, and acute lymphocytic leukaemia
- Previous cancer treatment: cancer patients treated with certain types of chemotherapy and radiation therapy may later develop acute myeloid leukaemia or acute lymphocytic leukaemia
- Family history: some people have a genetic susceptibility to developing leukaemia
- Chromosomal abnormalities: people with certain genetic conditions, such as Down syndrome, have a higher risk of developing leukaemia.
Signs, symptoms, and diagnosis
The symptoms of leukaemia are typically vague and non-specific and may be overlooked early in the disease because they resemble symptoms of influenza (the flu) and other common illnesses. Additionally, some forms of chronic leukaemia produce no symptoms initially and can go unnoticed and hence untreated for many years.
Depending on the type of leukaemia that's involved, symptoms may include:
- Fever or chills
- Fatigue and weakness
- Frequent infections
- Weight loss for no apparent reason
- Swollen lymph nodes and an enlarged liver or spleen
- Bone and joint pain
- Excessive sweating, particularly at night
- Bleeding and bruising easily
- Tiny red spots on the skin.
Treatment of leukaemia depends on the type of leukaemia, the extent of the disease, prior treatment, and the age and health of the patient. The aim of treatment is to destroy the leukaemia cell and make the symptoms go away. The types of treatment used for leukaemia include:
- Chemotherapy: the main form of treatment for leukaemia. It involves the use of chemotherapy drugs that kill leukaemia cells. Depending on the type of leukaemia, a single drug or a combination of drugs may be used.
- Biological therapy: this includes the use of drugs that work by helping the immune system to recognise and attack leukaemia cells.
- Targeted therapy: uses drugs that target specific vulnerabilities within leukaemia cells to inhibit their growth. For example, the drug imatinib stops the action of a specific protein that stimulates the growth of leukaemia cells in people with chronic myeloid leukaemia. This can help control the disease.
- Radiation therapy: uses x-rays or other high-energy beams to damage leukaemia cells and stop their growth. Radiation therapy may be used to prepare for a stem cell transplantation.
- Stem cell transplantation: a procedure in which diseased bone marrow is replaced with healthy bone marrow. Prior to a stem cell transplantation, high doses of chemotherapy or radiation therapy are given to destroy diseased bone marrow. An infusion of blood-forming stem cells that help to rebuild bone marrow is then given. A stem cell transplantation is very similar to a bone marrow transplantation.
Many people with acute leukaemia can be cured with immediate treatment.
Achieving cure in chronic leukaemia is more difficult. Chronic leukaemia without symptoms may not need immediate treatment – a watchful waiting approach may be taken and treatment started once symptoms start to appear.
When treatment for chronic leukaemia is given, its goal may be to control the disease and symptoms. Chronic leukaemia is not often cured with chemotherapy but stem cell transplantation may achieve cure in some people. Outcome (prognosis) depends on several factors. These include the patient’s age, type of leukaemia, extent to which the leukaemia has spread, and when in the course of the disease treatment is started.
The Cancer Society of New Zealand operates a phone service staffed by specialist nurses to support patients diagnosed with cancer, including leukaemia, as well as their friends and families. The Cancer Information Helpline Service can be contacted on 0800 CANCER (226 237). Information can also be obtained from the Cancer Society website: www.cancernz.org.nz.
Leukaemia & Blood Cancer New Zealand is a nationwide organisation dedicated to supporting patients living with leukaemia and related blood conditions. The organisation provides a toll-free number providing advice, empathy and support on 0800 15 10 15. More information can be obtained by visiting the website: www.leukaemia.org.nz.
Ministry of Health (2012). Cancer: Selected sites 2010, 2011, 2012. Wellington: Ministry of Health. http://www.health.govt.nz/publication/cancer-selected-sites-2010-2011-2012
O’Toole, M.T. (Ed.) (2013). Leukaemia. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis: Elsevier Mosby.
Stöppler, M.C. (2009). Leukemia. MedicineNet.com. New York: WebMD LLC. http://www.medicinenet.com/lung_cancer/article.htm