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What is chronic myeloid leukemia (CML)?

CML is a cancer of the bone marrow. It’s also called chronic myelogenous leukemia.

CML is caused by an abnormal chromosome in bone marrow cells called the Philadelphia chromosome. Chromosomes carry instructions that tell the body how to make everything it needs to work properly. The Philadelphia chromosome tells the bone marrow to make too many white blood cells. Doctors don’t know what causes the Philadelphia chromosome.

The 3 phases of CML

CML has 3 phases:

  1. Chronic phase – Most patients are diagnosed in this phase and often do not have any symptoms. During this phase, there are too many immature white blood cells (blasts) in the bone marrow, blood and spleen. Without treatment, the CML will move into the accelerated phase.

  2. Accelerated phase – During this phase, the number of blasts increase and the spleen gets bigger. Patients may have fevers, night sweats, weight loss and increasing fatigue.

  3. Blast phase – During this phase, the number of blasts in the blood stream grows quickly. This causes fewer normal blood cells (white blood cells, red blood cells and platelets). Patients may have very high fevers, night sweats, weight loss, shortness of breath, bruises, bleeding and infections.

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How does blood or marrow transplant (BMT) work for CML?

BMT, also known as bone marrow transplant or blood stem cell transplant, replaces the unhealthy blood-forming cells (stem cells) with healthy ones. For some people, transplant can cure their disease.

The most common type of transplant for CML is an allogeneic transplant. An allogeneic transplant uses healthy blood-forming cells donated by someone else to replace the unhealthy ones. These healthy cells can come from a family member, unrelated donor or umbilical cord blood. First, you get chemotherapy (chemo), with or without radiation, to kill the unhealthy cells. Then, the healthy donated cells are given to you through an intravenous (IV) catheter. The new cells travel to the inside of your bones and begin to make healthy blood cells.

The entire process, from when you start chemo or radiation, until hospital discharge, can last weeks to months. This is followed by many months of recovery near the transplant center and at home. Your transplant team will closely watch you to prevent and treat any side effects or complications.

When should I see a transplant doctor?

You should see a transplant doctor if:

  • The CML doesn’t get better with standard treatment. Most patients with CML take medicines called TKIs (tyrosine kinase inhibitors). These medicines may control CML for months or years.
  • The CML gets worse despite treatment with TKIs
  • You can’t take TKIs because of severe side effects or an allergy
  • The CML is in the accelerated or blast phase

Your first appointment with a transplant doctor

At your first appointment, the transplant doctor will:

  • Review your medical history
  • Talk with you about your treatment options
  • Discuss the risks and benefits of transplant
  • Recommend the best time for you to get a transplant and prepare for treatment
  • Start a donor search even if you don’t need it right away. This can help you get a transplant faster if it’s needed later

Questions to ask your doctor

Ask questions so you understand your treatment options and can make decisions that are best for you. Questions you may want to ask your doctor include:

  • What are my chances of a cure or long-term remission if I get a transplant? If I don’t get a transplant?
  • Does the phase of CML I have make a difference on how well transplant might work for me?
  • Does my current health or age affect how well transplant might work for me?
  • What are the possible side effects of transplant? How can they be reduced?
  • How might my quality of life change over time, with or without transplant?

 Learn more about planning for transplant


Most recent medical review completed March 2017.