Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Chronic Myeloid Leukemia (CML)


The Manual's Editorial Staff

Last full review/revision Jan 2020| Content last modified Jan 2020
Click here for the Professional Version
Get the full details

What is leukemia?

Leukemia is a cancer of white blood cells. White blood cells have many jobs, including helping your body's immune system fight off infection. White blood cells form in your bone marrow, the spongy tissue inside your bones.

With leukemia, you have a very high white blood cell count. However, the cancerous white blood cells don't work properly, so you're likely to get infections. Those infections may be life-threatening.

Also, the cancerous white blood cells fill up your bone marrow so it can't make normal blood cells such as:

There are many different types of white blood cells but only 2 main types of leukemia:

  • Lymphocytic leukemia: cancer of lymphocytes, which are one type of white blood cell

  • Myelogenous leukemia: cancer of all the other types of white blood cells

Lymphocytic and myelogenous leukemia can be acute or chronic:

  • Acute: cancer of young cells that spreads quickly and can cause death in 3 to 6 months if untreated

  • Chronic: cancer of mature cells that spreads more slowly

What is chronic myeloid leukemia (CML)?

Chronic myeloid leukemia (CML) is a type of slow-growing cancer of one of several different types of white blood cells. The cancer cells grow and spread into your blood and to other parts of your body.

  • CML happens most often in adults between ages 40 and 60

  • You may feel tired and have no appetite and lose weight

  • As the cancer grows, you may also be pale and bruise or bleed easily

  • Doctors find CML with blood tests and bone marrow exams

  • CML is treated with medicines called TKIs (tyrosine kinase inhibitors)

  • More than 90% of people treated early survive at least 5 years

CML has 3 stages:

  • Chronic phase: the first months or years when the cancer grows very slowly

  • Accelerated phase: the cancer begins to grow more quickly, treatments don’t work as well, and symptoms get worse

  • Blast phase: very young cancer cells called blasts show up and the cancer becomes much worse, with problems such as serious infections and bleeding

What causes CML?

CML is caused by a problem with one of your chromosomes. Each of your body's cells has 46 chromosomes. The chromosomes contain DNA, which determines how your cells work.

In CML, one of your chromosomes develops an abnormality. The abnormal chromosome is called the Philadelphia chromosome. It produces a substance that makes one type of white blood cell grow abnormally and out of control.

What are the symptoms of CML?

Early on, CML may cause no symptoms. When symptoms first appear, they may include:

  • Feeling weak and tired

  • Not feeling hungry

  • Weight loss

  • Fever

  • Sweating at night

  • Feeling a fullness in the upper belly (due to a large liver and spleen)

Later, you may become sicker and have symptoms such as:

  • Fever (from infections or the leukemia)

  • Bruising

  • Bleeding

How can doctors tell if I have CML?

To tell if you have CML, doctors will:

  • Do blood tests

  • Take a sample of your bone marrow to test (bone marrow exam)

  • Do molecular testing to look for the Philadelphia chromosome

How can doctors treat CML?

Doctors treat CML with:

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Test your knowledge

Polyglandular Deficiency Syndromes
Polyglandular deficiency syndromes are hereditary disorders in which several endocrine glands (ie, glands that secrete hormones) malfunction together. Which of the following is the most appropriate treatment for these types of disorders? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID