What is chronic myeloid leukemia?

Chronic myeloid leukemia, also known as CML or chronic myelogenous leukemia, is a type of cancer that starts in the soft center part of your bones, called bone marrow. This is the part where your blood cells are made.

In CML, the cancer cells build up and fill your bone marrow and spill out into your blood leading to spreading to other organs. Most people who get CML are middle-aged or older, and many people don’t know they have CML.

The leukemia is considered "chronic" when the leukemia cells build slowly over time, versus types of acute leukemia that grow rapidly.

Common related conditions
Leukemia Acute Myeloid Leukemia (AML) Chronic Lymphocytic Leukemia (CLL)

Causes of chronic myeloid leukemia

CML occurs immature (early) versions of myeloid cells grow out of control due to DNA mutations. These DNA changes allow cells to build up and grow into cancer.

CML starts with a mutation called BCR-ABL that happens when parts of two chromosomes (pieces of DNA) switch places, making a new structure called “the Philadelphia chromosome.” The BCR-ABL mutation on the Philadelphia chromosome causes cells in the bone marrow to grow and become cancer.

Risk factors from chronic myeloid leukemia

Scientists know some things that may increase the risk of developing CML, including:

  • Radiation exposure — CML is more common in those who have been exposed to high-dose radiation.
  • Age — CML is more common in older people than in younger people.
  • Gender — CML is slightly more common in men than in women.

Symptoms of chronic myeloid leukemia

CML is often hard to diagnose as many symptoms presents as other conditions.

Common symptoms include:

  • Weakness or fatigue
  • Night sweats
  • Fevers
  • Unexplained weight loss
  • Bone pain
  • Pain or swelling on the left side of your abdomen
  • Frequent infections

Diagnosis of chronic myeloid leukemia

Doctors often find CML when they check routine blood tests for other reasons.

If a doctor suspects CML, they may order:

  • Complete blood count — your doctor may order a blood cell count, which can give information about the types of cells that are in your blood stream.
  • Blood smear — your doctor may also order a blood smear, where they can examine your blood under a microscope to look for cells that look cancerous.
  • Bone marrow biopsy — a procedure where a small amount of the bone marrow is removed so that a doctor can examine it under a microscope.
  • Genetic Tests — your doctor may want to look at your entire DNA, or they may look for certain genes and mutations that signal CML.
  • Imaging — imaging tests, like CT scan or MRI, help when looking for the cause of some symptoms, but they are not necessary to diagnose CML.

Treatments for chronic myeloid leukemia

Treatment for CML aims at destroying leukemia cells so that normal ones can grow back.

Doctors usually start with medications called Tyrosine Kinase Inhibitors (TKIs). Some TKIs, for example, are Dasatinib (Sprycel), Imatinib (Gleevec), and Nilotinib (Tasigna). If two different TKIs don’t work, your doctor may offer you a more intense medication to boost your immune system to fight the leukemia.

Stem cell transplant
If all other treatments fail, a stem cell transplant can be used to cure CML in some people. Stem cells are normal cells harvested from a healthy person’s bone marrow. Your doctor injects stem cells into your blood and they plant themselves in your bone marrow. They usually use chemotherapy first, then the transplant. The idea is that they replace the cancerous cells so that your bone marrow can be healthy again.

Finding a bone marrow donor is tricky. Donors have to be genetically similar to you; so many times siblings test to see if they can be donors. If you don’t have siblings or your siblings aren’t a match, you can add your name to a list of people waiting for a bone marrow transplant from a stranger.

Recovery from chronic myeloid leukemia

Recovery from CML depends on the type of treatment. Your doctor will likely want you to follow closely in the office during and after treatment.

There is a chance that CML can come back even though it has been treated. Make sure to attend all your follow-up appointments.

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