How chronic myeloid leukaemia is diagnosed
Because there are few, if any, symptoms to begin with, it’s common for people with CML to be diagnosed by chance when they have a blood test for another reason.
The blood test shows a high number of white blood cells called granulocytes that are more immature than normal.
If your GP suspects you have CML, they will refer you to a haematologist for specialist advice and treatment.
A haematologist is a doctor who specialises in the treatment of blood problems.
The haematologist will ask about any illnesses or health problems you’ve had. They will also examine you to check if your lymph nodes, spleen or liver are enlarged. You’ll have more blood samples taken to check the number of different cells in your blood (a full blood count) and to look for leukaemia cells.
If the blood test shows there are leukaemia cells in your blood, the haematologist will arrange further tests to find out what type of leukaemia you have and its extent. The results of these tests will help them plan your treatment.
Bone marrow sample/biopsy
A small sample of bone marrow is taken from the back of the hip bone (pelvis) or occasionally the breastbone (sternum). It’s looked at under a microscope to see if it contains any abnormal white blood cells. A haematologist can tell which type of leukaemia it is by identifying the type of abnormal white cell. Other tests will also be carried out on the sample to help confirm the diagnosis and plan treatment. These may include cytogenetics and molecular tests (PCR test), which help to identify the abnormal fusion gene.
Before the bone marrow sample is taken you’ll be given a local anaesthetic injection to numb the area. A thin needle is then passed through the skin into the bone. A small sample of the bone marrow is drawn into a syringe to be examined under a microscope. The procedure can be done on the ward or in the outpatient department, and takes about 15–20 minutes.
It can be uncomfortable when the bone marrow is drawn into the syringe, but this should only last for a few minutes. You may be offered a sedative to reduce any pain or discomfort.
Sometimes, a small core of marrow is needed (a trephine biopsy), and this procedure takes a few minutes longer.
A slightly thicker needle is passed through the skin into the bone marrow. The doctor will push the needle in and then rotate it so that when the needle is removed, it will contain a 1–2cm piece of bone marrow.
You may feel bruised after having a sample of bone marrow taken, and have an ache for a few days. This can be eased with mild painkillers.
You may have additional tests, which may include the following:
A chest x-ray may be taken to check your heart and lungs are healthy.
An ultrasound scan may be done to see if your liver and spleen are enlarged. Ultrasound uses sound waves to build up a picture of the inside of the body. It’s a painless test and only takes a few minutes.
The blood and bone marrow sample will be analysed to look for the Philadelphia chromosome. These tests are called cytogenetic tests and can help doctors decide on the best treatment for you.
PCR (polymerase chain reaction) test
This is a blood test that detects the abnormal fusion gene called BCR-ABL, which is usually present in CML. It’s a very sensitive test and can detect tiny amounts of leukaemia that can be missed by other tests. It’s used to confirm the diagnosis of CML and to monitor the response to treatment.