What is chronic myeloid leukaemia?

Chronic myeloid leukaemia (CML) is the rarest of the four main types of leukaemia, and involves abnormalities in some of the white blood cells. CML affects people of all ages and the exact cause is unknown. The main treatments used for CML are a drug called Glivec, chemotherapy, and a stem cell or bone marrow transplantation.

What blood cells are affected?

CML affects the myeloid line of cells, which consists of four types of blood cells: granulocytes, monocytes, red blood cells and platelets. With CML, it is the granulocytes, which get rid of infectious invaders in the body, that are most affected.

In CML large numbers of abnormal mature cells start appearing in the circulating blood, with the disease progressing slowly to begin with.

Also see: Blood cell types

What are the symptoms of CML?

People with CML may experience a variety of symptoms including fatigue, sweats, or weight loss. Sometimes a lump might be felt under the lowest rib on the left side which is due to an enlarged spleen.

What causes CML?

The disease affects women and men of all ages and, like many other forms of leukaemia, the cause is unknown.

People exposed to high doses of radiation, such as survivors of the Hiroshima bomb in 1945, and people who have received radiation therapy for a variety of medical conditions, have a slightly higher chance of getting CML in later years.

For most people, though, radiation probably plays no part in causing the disease and there are no other known risk factors.

The possible involvement of other environmental agents such as drugs, chemicals, or viruses has still not been determined.

How is CML diagnosed?

CML is usually identified by examining a blood sample, taken either at the hospital or a GP's surgery, under a microscope.

If the disease is present, cells normally only found in the bone marrow will also be present in the blood. To confirm the diagnosis a haematologist will also usually examine a sample of the patient's bone marrow.

In CML, each of the abnormal bone marrow cells displays a very characteristic change in one of its chromosomes, which carries the genetic information of the cell. This abnormal chromosome, which is a shortened number 22, is referred to as the 'Philadelphia chromosome' after the city where it was first identified in 1960.

Treatment goals

Treatment of chronic stage CML has two aims:

• to control the disease, getting it to a level the body is able to cope with, while minimising the side effects; and
• preventing or delaying the onset of the acute phase.

Each person's disease is slightly different and the exact treatment will vary from one individual to another.

What are the types of treatment?

The main treatments used for CML are a drug called Glivec, chemotherapy and a stem cell or bone marrow transplantation.

Glivec is a unique treatment that targets the molecular abnormality that causes CML. With CML there is a constant signal that tells the body to keep producing abnormal white blood cells. Glivec works to block, or turn off that signal.

A real advantage of this treatment is that healthy cells are left unharmed, so most patients taking Glivec do not have a major problem with side effects.

As with most drugs, there is always the potential of side effects. In relation to Glivec these symptoms can be relieved by specific medications and should be discussed with nursing or medical staff.

Related topics

Also see Leukaemia and Acute myeloid leukaemia

What does that term mean? See Cancer glossary

Original material provided by the Leukaemia and Blood Foundation of New Zealand, 2007. Edited by everybody, August 2010.