Tests before and after diagnosis

Not everybody will need every test available, but these are some of the tests you may have:

The full blood count (FBC) will measure:

• your haemoglobin concentration – the substance in red blood cells that carries oxygen around the body (Hb)
• the overall number of white blood cells in your blood (WBC)
• the number of platelets in your blood (Plt)
• the number of white blood cells called neutrophils in your blood (Neut)

The letters in brackets are what you may see written on your test results. You can ask your hospital team to go through the results with you and explain what all the figures mean.

A bone marrow biopsy is a minor surgical procedure done in hospital as a day patient. It takes around half an hour in total, and you should be able to go home shortly afterwards.

During the biopsy, samples of your blood cells will be taken from the bone marrow at the back of your pelvis. You'll have a local anaesthetic to numb the area where the needle goes in. People's experiences of this vary, and some feel a pushing or pulling sensation that might be uncomfortable. Others find it painful, even with the anaesthetic. Read our suggestions for what you can do to make having a bone marrow biopsy more manageable.

Your results will probably take one to two weeks to come through. Ask your doctor or nurse when to expect them.

If you are taking any anticoagulant medication such as warfarin or apixaban, you may need to stop taking it for a short period of time before having a bone marrow biopsy. Your hospital team will be able to tell you more about this if it applies to you.

Every three months, you will need to have a genetic test known as a BCR::ABL1 test. This is sometimes called a PCR test, as it uses a technology called polymerase chain reaction.

The BCR::ABL1 test uses a sample of blood or bone marrow to check for the BCR::ABL1 gene, found in the Philadelphia chromosome. The BCR::ABL1 gene produces a tyrosine kinase protein, which causes cancer cells to divide quicker and live longer than healthy cells. TKI medication aims to stop this protein from being produced by the BCR::ABL1 gene, so this test tells doctors how well your treatment is working.

During your treatment, your hospital team will run regular tests to monitor the CML and any side effects you experience. It’s really important to attend all your appointments as these tests measure your response to the treatment you’re on.

At the beginning, you’ll have tests more regularly – usually every 3 months at most. If your results are stable, this might change to every 3-6 months. The tests you’ll need are the same as the ones that diagnose CML, but you probably won’t have to have a bone marrow biopsy unless your results change a lot or your treatment doesn’t work the way your doctor expects it to.

The tests you have throughout your treatment for CML will measure how well the treatment is working. There are several levels of response that doctors expect to see, and you normally achieve these one by one depending on how long you’ve been having treatment.

When your blood counts return to normal, you’re said to have achieved a complete haematological response (CHR). This usually happens around three months after starting treatment.

This can be confusing, because although your counts are classed as normal, you still have CML and if you stopped treatment at this stage, it is very likely that it would come back just as quickly. Continuing treatment will help to keep things under control.

This is another way of measuring how you’ve responded to the treatment you’re on. Doctors will usually perform a genetic test on a sample of your blood or bone marrow to see how many of your cells contain the Philadelphia chromosome or the abnormal BCR::ABL1 gene.

If the tests can’t detect the Philadelphia chromosome, or they show that your level of the BCR::ABL1 tyrosine kinase protein released by the new abnormal gene is less than 1%, you are said to have achieved a complete cytogenetic response (CCyR).

The BCR::ABL1 or PCR test is a molecular test and is the best way to monitor levels of leukaemia in the blood. The results of these tests can be explained in percentages, and they tell you what proportion of your blood cells are leukaemia cells. It’s normal for your results to go up and down over time, but if you have any concerns, speak to your hospital team.

• If you have less than 1 leukaemia cell in every 1000 blood cells (<0.1%) this is known as a major molecular response (MMR).
• If you have less than 1 leukaemia cell in every 10,000 blood cells (<0.01%), this is known as deep molecular response (MR4).
• If you have less than 1 leukaemia cell in every 32,500 blood cells (<0.0032%), this is called MR4.5
• If you have less than 1 leukaemia cell in every 100,000 blood cells (<0.001%), this is called MR5.

Once you’ve achieved MMR, you’ll still have regular tests, but you may be able to have them slightly less often.

If you’re hoping to pause or stop treatment completely in the future, you’ll need to achieve a sustained MR4 or better for at least 3 years.

If no cancer cells at all can be detected in your PCR tests, you might hear your results referred to as ‘undetectable transcripts’. There might still be an incredibly small number of these cells somewhere in your body, but the test hasn’t been able to pick them up.

This is also sometimes called a complete molecular response (CMR).