What is chronic myeloid leukaemia (CML)?
Chronic myeloid leukaemia (CML) is a type of blood cancer that causes myeloid stem cells in your bone marrow to overproduce a type of white blood cell called a ‘granulocyte’.
White blood cells usually help the body fight infections, but the cells are slightly underdeveloped if you have CML. This means they can’t do their job properly.
Over time, these white blood cells slowly start filling up your bone marrow. When your bone marrow gets too full, it cannot produce all the different types of healthy blood cells your body needs.
You might also hear CML called ‘chronic granulocytic leukaemia’ (CGS).
How many people are diagnosed with CML?
Around 800 people are diagnosed with CML each year in the UK. It is more common in people over the age of 60.
I was showing symptoms for around a month, which included fatigue, night sweats, weight loss and bruises that wouldn’t heal. But I was working in construction and renovating our first home during a heatwave, so I put it down to that. Once I was finally in hospital, I was there for three months.
Ricky, who had a stem cell transplant to treat chronic myeloid leukaemia (CML)
Treatments for CML
Your treatment will depend on which stage – or ‘phase’, as doctors call it – of CML you’re at. There are three phases in total:
- Chronic phase
- Accelerated phase
- Blast phase
Most people with CML get a diagnosis during the ‘chronic phase’. At this stage, doctors can treat you with a type of drug called tyrosine kinase inhibitors (TKIs). TKIs help block the enzymes that cause cancer cells to keep dividing and growing.
Another option for treating CML is an allogeneic stem cell transplant – this is when someone donates their stem cells to you. Doctors might offer you a stem cell transplant for either one of these reasons:
- Your body has not responded well to the TKIs that block the enzymes.
- You’re experiencing ‘blast phase’ of CML – also known as ‘blast crisis’ – and need to get it back to ‘chronic phase’. At blast phase, there is a risk that CML might develop into acute myeloid leukaemia (AML).
How many people have a stem cell transplant to treat CML?
There were 47 stem cell transplants in the UK to treat CML in 2023.
Where to find support for CML
Anthony Nolan supports people with all sorts of conditions that might use stem cells or cell therapies for treatment. But other organisations support people affected by specific blood cancers like CML.
To find out more about CML symptoms, diagnosis and treatments, you can visit:
To find advice and support for living with cancer, you can visit:
I certainly try and enjoy life more now, which sounds so cliché but it is true. Even simple things. I remember a day in particular on my own walking the dog, just a normal field, nothing special about it and just thinking: 'Wow I’m lucky, this is so nice.'
Alex, who received a stem cell transplant to treat chronic myeloid lekaemia (CML). You can read his story on our blog.
Information last updated: 12/05/2025
Next review due: 12/05/2026