Chronic myeloid leukaemia

Leukaemia is a cancer of white blood cells. The term chronic leukaemia is used to describe the type of cancer that progresses slowly over many years, people with chronic leukaemia often show few symptoms for many years. This means that the condition is often diagnosed coincidentally, during routine check-ups or blood tests for other issues.

Chronic myeloid leukaemia is further classified according to the type of white blood cells that are affected by cancer – the myeloid cells, which perform a number of different functions, such as fighting bacterial infections, defending the body against parasites and preventing the spread of tissue damage.

Risks and causes of chronic myeloid leukaemia

What triggers the development of chronic myeloid leukaemia and causes the initial mutation in stem cells is unknown, although there are many suspected risk factors. There is some evidence to show an increased risk of chronic myeloid leukaemia in people who:

• Are obese
• Have a weakened immune system – due to HIV or AIDS or taking immunosuppressants after an organ transplant
• Have inflammatory bowel diseases – such as ulcerative colitis or Crohn’s disease
• Have been exposed to high levels of radiation

It is quite a rare type of cancer.

Symptoms of chronic myeloid leukaemia

In its early stages, chronic myeloid leukaemia usually causes no noticeable symptoms and is often diagnosed during tests for a different condition. When symptoms do develop, they are similar to those of many other illnesses and can include:

• Tiredness
• Frequent infections
• Unexplained weight loss
• A feeling of bloating
• Less commonly, swollen lymph nodes – glands found in the neck and under your arms, which are usually painless

Chronic myeloid leukaemia can also cause swelling in your spleen (an organ that helps to filter impurities from your blood). This can cause a lump to appear on the left side of your abdomen, which may be painful when touched. A swollen spleen can also put pressure on your stomach, causing a lack of appetite and indigestion.

If any of these symptoms apply to you, or if you have any concerns about similar symptoms, it is essential that you see your doctor at once, as your chances of recovery are much higher if your cancer is diagnosed early.

How is chronic myeloid leukaemia diagnosed?

Most cases of chronic myeloid leukaemia are often first detected when a routine blood test is carried out to diagnose another, unrelated, condition. Once CML is suspected, tests include:

• Blood test: to check for a high number of abnormal white blood cells in the sample
• Bone marrow biopsy: a haematologist will take a small sample of bone marrow to examine under a microscope. This involves inserting a needle into a large bone, usually the hip bone, to extract the marrow and is done under local anaesthetic
• Cytogenetic testing involves identifying the genetic make-up of the cancerous cells. There are specific genetic variations that can occur during leukaemia, and knowing what these variations are can have an important impact on treatment
• A polymerase chain reaction (PCR) test can be done on a blood sample. This is an important test to diagnose and monitor the response to treatment
• CT scan: shows a 3D image of the area being looked at
• X-ray: low-level radiation is used to create an image of the body

Chronic myeloid leukaemia treatment

Patients with CML are treated by a team of different specialists called a multidisciplinary team. This team works together to create a treatment plan to suit the individual needs of the patient. Because CML is a chronic condition, the first treatment is usually medication to stop the progression of the cancer.

Imatinib tablets are usually given as soon as you have been diagnosed with chronic myeloid leukaemia, to slow its progression. These tablets are taken every day for life, and most patients do really well on them.

The aim of treatment is to achieve the following:

• After three months, correct the blood count
• By 12 months, clear the bone marrow of cells containing the Philadelphia chromosome
• By 18 months, get to a stage where the leukaemia can only be detected by a very sensitive molecular test (molecular remission)

If the leukaemia reaches an advanced stage, further treatment is considered, including:

• Chemotherapy involves the use of chemical agents which are toxic to cancer cells, destroying them and preventing them from spreading to different areas. This can be given by injection or in tablet form
• A bone marrow or stem cell transplant is a possible alternative if chemotherapy has been unsuccessful. Before transplantation can take place, the patient will need to have intensive high-dose chemotherapy and radiotherapy to destroy the cells in their bone marrow. The donated stem cells are then given through a tube into a blood vessel, in a similar way to chemotherapy medication