Leukaemia is a cancer that affects the blood and bone marrow where blood cells are made.
People sometimes confuse leukaemia and lymphoma. Leukaemia is a cancer of the blood; lymphoma is cancer of the lymphatic system (lymph glands).
The word “Leukaemia”, which means “white blood”, is a cancer which starts in blood-forming tissue, usually the bone marrow. It leads to the over-production of abnormal white blood cells , the part of the immune system which defends the body against infection. These white blood cells are not fully developed and are called blasts or leukemia cells.
Blood cells are formed in the bone marrow, the spongy tissue found inside the bones. Blood-forming stem cells divide to produce either more stem cells or immature cells that become mature blood cells over time.
The DNA of immature blood cells, mainly white cells, becomes damaged in some way. This abnormality causes the blood cells to grow and divide continuously. Healthy blood cells die after a while and are replaced by new cells, which are produced in the bone marrow.
The abnormal blood cells do not die when they should, and accumulate, occupying more space. As more cancer cells are produced, they impede the function and growth of healthy white blood cells by crowding out space in the blood. Essentially, the bad cells crowd out the good cells in the blood.
A blood stem cell may become a myeloid stem cell or a lymphoid stem cell.
A myeloid stem cell becomes one of three types of mature blood cells:
Red blood cells that carry oxygen to all tissues of the body.
Platelets that form blood clots to stop bleeding.
Granulocytes (white blood cells) that fight infection and disease.
A lymphoid stem cell becomes a lymphoblast cell and then one of three types of lymphocytes (white blood cells):
B lymphocytes that make antibodies to help fight infection.
T lymphocytes that help B lymphocytes make the antibodies that help fight infection.
Natural killer cells that attack cancer cells and viruses.
Leukaemia affects white blood cells and can be classified by the type of white cell affected (myeloid or lymphatic) and by the way the disease progresses (acute or chronic). Acute and chronic do not refer to how serious the disease is but to how rapidly it progresses.
The most common forms of leukaemia in adults are CLL and AML, and the common cancer in children is ALL. Leukaemia is more common in adults. Leukaemia is slightly more common in men than women.
Acute leukaemia progresses rapidly, unless effectively treated but it can often be cured with standard treatments, such as bone marrow transplants, especially in younger and/or fitter patients,
Chronic leukaemia progresses slowly but, although it can be treated and managed, it is not usually possible to cure chronic leukaemia with standard treatments.
Causes of Leukaemia
There is no single known cause for any of the different types of leukaemia. However, it is important to understand that:
Leukaemia is not a condition which can be caught from someone else (contagious)
Leukaemia is not passed on from a parent to a child (inherited)
Age - most forms of leukaemia are more common in older people. The main exception to this is ALL in which peak incidence is in children
Gender - leukaemia is generally more common in males
Genetics - although leukaemia is not an inherited disease, there is a slightly higher chance that close relatives of patients may develop some forms of leukaemia. The risk is still very small and there is no cause for anxiety or for screening tests
Chemical exposure - being exposed to some chemicals and high levels of radiation may increase the chance of developing leukaemia. These factors account for only a very small proportion of all cases
Some forms of leukaemia are seen more commonly in people who have other bone marrow disorders. The most common disorders which behave in this way are myelodysplastic syndrome (MDS) and the myeloproliferative neoplasms (MPN)
Signs and Symptoms
Signs and symptoms of leukaemia generally are notoriously vague and non-specific. There are no specific signs or symptoms of any type of leukaemia which would allow a doctor to make a diagnosis without laboratory tests.
In all types of leukaemia, symptoms are more commonly caused by lack of normal blood cells than by the presence of abnormal white cells. As the bone marrow becomes full of leukaemia cells, it is unable to produce the large numbers of normal blood cells which the body needs. This leads to:
Anaemia – due to lack of red blood cells.
Weakness, tiredness, shortness of breath, light-headedness, palpitations.
Infections – due to lack of normal white blood cells.
Infections are more frequent, more severe and last longer.
Fever, malaise (general feeling of illness) and sweats.
Purpura (small bruises in skin), heavy periods, nosebleeds, bleeding gums.
Loss of appetite and weight.
Discomfort under the left lower ribs (caused by a swollen spleen).
Blood clotting problems. This is due to low levels of platelets in the bloodstream. This can cause easy bruising, bleeding from the gums and other bleeding-related problems.
In advanced stages, symptoms may include sudden high temperature, confusion, seizures, inability to talk or move limbs, and an altered state of consciousness.
There are some symptoms that are only seen in certain patients or forms of leukaemia. For example, young children with ALL may complain of pain in bones or joints and, in some types of AML, the gums may be swollen by leukaemia cells in the tissues.
In lymphoid malignancies, lymph nodes (glands) may be swollen. In some forms of the leukaemia the liver may be enlarged (hepatomegaly) or the spleen (an organ of the immune system found just under the ribs on the left hand side) may be enlarged (splenomegaly).
How to Diagnose Leukaemia
Diagnosis is usually based on repeated complete blood counts and a bone marrow examination following observations of the symptoms. Sometimes, blood tests may not show that a person has leukaemia, especially in the early stages of the disease or during remission. A lymph node biopsy can be performed to diagnose certain types of leukaemia in certain situations.
Following diagnosis, blood chemistry tests can be used to determine the degree of liver and kidney damage or the effects of chemotherapy on the patient. When concerns arise about other damage due to leukaemia, doctors may use an X-ray, MRI, or ultrasound. These can potentially show leukaemia's effects on such body parts as bones (X-ray), the brain (MRI), or the kidneys, spleen, and liver (ultrasound). CT scans can be used to check lymph nodes in the chest, though this is uncommon.
Despite the use of these methods to diagnose whether or not a patient has leukaemia, many people have not been diagnosed because many of the symptoms are vague, non-specific, and can refer to other diseases. For this reason, the American Cancer Society estimates that at least one-fifth of the people with leukaemia have not yet been diagnosed.
Treatment of Leukaemia
If you are being treated for any type of leukaemia, you may be asked to consider taking part in a clinical trial. Clinical trials are scientific studies to find the best treatment.
Some patients who have leukaemia do not start treatment straight away. If patients are not being treated they have regular check-ups. This is known as “watch and wait” or “active monitoring”. This is mainly relevant for patients with CLL. Almost all patients with CML or with acute leukaemia will start treatment soon after diagnosis. Some patients with CLL will never need to receive treatment for their leukaemia.
Although patients on watch and wait do not have to deal with side effects of treatment, it can be an incredibly anxious time. If this applies to you it is important to let your healthcare team know, as they can offer support and reassurance.
Acute leukaemia is often curable with standard treatments. Chronic leukaemia is usually not curable, but treatable. Although most patients with chronic leukaemia have a good initial response to treatment the condition will sometimes come back, this is known as a relapse and it can usually be treated again, using similar treatments as were used the first time.
The main ways in which leukaemia is treated are:
Chemotherapy - cell-killing drugs. Steroids are normally used along with chemotherapy for lymphoid leukaemia
Radiation therapy - usually only for stem cell transplant or local disease e.g. in spleen
Targeted therapy - drugs which specifically recognise and kill leukaemia cells
Biological therapy - treatments which use the immune system to destroy leukaemia cells. Often these use antibodies against markers on the leukaemia – these are known as monoclonal antibodies.
Stem cell transplant - Younger/fitter patients may be given a stem cell transplant (bone marrow transplant). This may be done using your own healthy stem cells or stem cells from a donor. This is most commonly done for acute leukaemia if chemotherapy does not cure the disease.
Chemotherapy is the use of cell-killing drugs. These kill the cancer cells and/or stop them from dividing. Chemotherapy is usually given in blocks or ‘cycles’ of treatment. One cycle of treatment will consist of a series of doses of chemotherapy followed by a break for the healthy cells to recover.
Chemotherapy is normally given as a combination of drugs, which, for lymphoid leukaemia, will usually include steroids. Steroids used to treat lymphoid leukaemia are a laboratory-made version of chemicals naturally made by the body. They are very different from the type of steroids sometimes misused by body builders or sportsmen.
The details of the treatment will vary depending on the features of the leukaemia and the patient’s general fitness. Patients will be given a chance to discuss treatment options and detailed information on the treatment plan before it starts. The side effects of treatment vary between different types of treatment and different patients. Patients will be given detailed information about any likely side effects before treatment starts.
Leukaemia Prognosis and Life Expectancy
The success of treatment depends on the type of leukaemia and the age of the person.
All leukaemia patients, regardless of what type they have or had, will need to be checked regularly by their doctors after the cancer has gone (in remission). They will undergo exams and blood tests. The doctors will occasionally test their bone marrow. As time passes and the patient continues to remain free of leukaemia the doctor may decide to lengthen the intervals between tests.
Outcomes have improved in the developed world. In children with acute leukaemia who are cancer-free after five years, the cancer is unlikely to return.
Outcomes depend on whether it is acute or chronic, the specific abnormal white blood cell type, the presence and severity of anaemia or thrombocytopenia, the degree of tissue abnormality, the presence of metastasis and lymph node and bone marrow infiltration, the availability of therapies and the skills of the health care team. Treatment outcomes may be better when people are treated at larger centres with greater experience.