Family doctor

Overview:

• Leukaemia is a cancer of the blood cells which are made in the bone marrow
• There are several types of leukaemia
• Leukaemias are placed in two categories: acute and chronic
• Acute leukaemia acts quickly and can be cured in many cases; chronic leukaemia can take years to develop, is more difficult to cure, but can often be kept under control for many years
• Acute lymphocytic leukaemia is the most common childhood leukaemia
• Symptoms include those related to bone marrow failure (anaemia, infections and bruising, and those related to the expanding number of leukaemia cells (swollen glands, enlarged liver and spleen)
• It is often not known what causes leukaemia in a particular individual but there are risk factors such as radiation, chemicals such as benzene, radium, some chemotherapy drugs, and some viruses have a genetic predisposition in some individuals
• Treatment often involves chemotherapy and bone marrow transplants, as well as support care (transfusions, antibiotics).

What is it?

Leukaemia is a cancer of the blood cells. It is characterised by a large number of abnormal white blood cells in the bone marrow, and a lack of normal blood cells.

About 10 people in every 10,000 will get leukaemia.

There are several types of leukaemia which are classified as acute or chronic.

Acute leukaemia progresses very quickly, sometimes people can became ill in just a few weeks. Chronic leukaemia develops slowly and can take years before it is noticed.

Less than half of leukaemia cases are due to acute leukaemia. However, 85 percent of childhood leukaemias are due to this type, with those aged one to five most at risk.

Chronic leukaemias are mainly found in those over 50 years of age.

The most common types of leukaemia are:

• Acute lymphocytic leukaemia. This is the most common type in children but it can also affect adults.
• Acute myeloid leukaemia. This affects both adults and children.
• Chronic lymphocytic leukaemia. This hardly ever affects children. It is mainly found in adults over 50.
• Chronic myeloid leukaemia. This mainly occurs in adults.
• Hairy cell leukaemia. This is a rare form of chronic leukaemia.

It is often not known what causes leukaemia, which is more common in males than females.

Some risk factors include exposure to high amounts of radiation, such as nuclear disasters like Hiroshima and Chernobyl.

There is a genetic risk in a few families. Children born with Down's syndrome and some other conditions such as Fanconi anaemia are more prone to leukaemia. There is an increased rate of some types of leukaemia among identical twins.

Exposure to certain chemicals such as benzene over a long period may increase the likelihood of developing leukaemia.

One rare form of leukaemia is caused by a retrovirus.

What are the symptoms?

Symptoms of leukaemia are similar to many other conditions and often blood tests are the only way the disease is discovered.

Those with acute leukaemia complain of tiredness, weakness, and flu-like symptoms such as fever and chills. They may have had a bleeding nose or gums, mouth ulcers, and a sore throat.

They are more prone to infections, they may have anaemia, and look pale and bruise easily.

When the disease has progressed it can cause enlargement of the liver, spleen, and lymph glands.

There may be no symptoms with chronic leukaemia. This is often diagnosed when blood tests are ordered for other reasons.

People with chronic myeloid leukaemia may complain of tiredness, weight loss, breathlessness, and stomach pain. There is an enlarged spleen in the majority of cases.

Those with chronic lymphocytic leukaemia are often very well in the early stages which can continue for years. Some have weight loss, fever, lethargy, and may feel unwell. As the leukaemia progresses, the white count can dramatically increase and this is often associated with swollen glands and spleen. Infections can increase due in part to reduced antibody levels. This is the most common type of leukaemia and is mainly found in those over 50 years of age.

Blood tests are used to diagnose leukaemia, though often bone marrow tests are needed to confirm the type.

Other tests are carried out if leukaemia is discovered - these may include tests for liver and kidney function, x-rays of the liver and spleen, and investigations for infections.

What is the treatment?

Chemotherapy is the main treatment for acute leukaemia. The drugs used depend on the age of the patient and the type of leukaemia.

There are three phases of chemotherapy. The first phase is designed to destroy as many leukaemia cells as possible (remission induction), using several drugs to prevent the development of drug resistance in the cells.

The second phase (consolidation) is aimed at ensuring that any residual cells are destroyed, and in some cases, there is a third phase aimed at maintaining remission.

If chemotherapy fails to induce remission where the leukaemia is undetectable and the normal blood cells recover to normal, the prognosis is generally poor.

If the patient has no sign of leukaemia after five years, they can be regarded as being cured. If a leukaemia relapses, it can often be treated again - the longer the period before relapse, the more successful the second round of treatment.

Bone marrow transplants offer the best hope of a cure for those whose disease has relapsed, and for some patients whose initial tests suggest that a cure is less likely just with chemotherapy.

Ideally, bone marrow from a compatible brother, sister, or family member is used. Most patients do not have a family donor and then searches are made in the international bone marrow donor registries - currently there are more than six million volunteers registered as potential bone marrow donors who have had preliminary compatibility tests done.

Some people may decline treatment. Intensive chemotherapy may be too severe for those over 70 years, people with other fatal or severe diseases, and those with secondary cancer. In such cases, a more gentler form of treatment and support care, including transfusions and antibiotics can keep a patient alive for months in some cases.

About 80 percent of those under 60 with acute leukaemia go into remission following treatment. Treatments have improved over the past two decades, so that about 40 percent of adults with acute myeloid leukaemia now have a long life after treatment.

Fifty to sixty percent of children who are treated are cured. Those who are not treated are likely to die within a few months.

Chronic lymphocytic leukaemia has a median survival rate of six years - many patients presenting early may live for 20 years or more. When treatment is needed, this involves a milder form of chemotherapy with very few side effects.

Chronic myeloid leukaemia has a median survival rate of five years, but some people will survive over 10 years if they respond to interferon treatment. Some younger patients with this condition (usually under 45 years of age) are cured with a bone marrow transplant.

Future trends

Many researchers around the world are studying the disease to find out more about the cancer and develop new treatment options, and hopefully find a way to prevent it.

Scientists are studying viruses and other risk factors for leukaemia.

A new drug, retinoic acid, used successfully to treat promyelocytic leukaemia (a type of acute myeloid leukaemia) is a form of vitamin A.

Getting help

Your doctor, or haematology department at your nearest large hospital will be able to help.

The Leukaemia and Blood Foundation 09 308 0240.

The Cancer Society, Auckland Ph 09 524 0023 or free phone 0800 800 426.

The Child Cancer Foundation, head office, Ph 09 3733670.

The New Zealand Bone Marrow Donor Registry coordinates searches for unrelated bone marrow donors nationally and internationally for all New Zealand patients. Ph Auckland 09 309 8122. The registry is currently recruiting Maori and Pacific Island healthy blood donors as bone marrow donors for a number of patients who are desperately looking for donors.