Chronic myelomonocytic leukemia (CMML) is a rare type of blood cancer. Some people live a long time with CMML, but others go on to develop acute myeloid leukemia (AML).
Chronic myelomonocytic leukemia (CMML) is a chronic type of blood cancer. This means it develops more slowly than acute leukemias. There is currently no cure, but drug treatment, chemotherapy, and stem cell treatment can help manage it and may lead to remission.
Here, we look at what CMML is, why it happens, the treatment options, and the outlook for a person with this type of leukemia.
CMML is a rare type of blood cancer. In the United States,
CMML usually affects older adults and is rare in young people. In children, it is called juvenile myelomonocytic leukemia (JMML).
In CMML, two changes occur.
One is that alterations in the DNA of blood cells affect blood cell production.
The other is that the body starts producing too many immature white blood cells, known as blasts. These cells enter the bloodstream and crowd out other blood cells. These white blood cells never reach maturity and are unable to keep the body healthy.
People with CMML may have low levels of certain blood cells or too many blood cells overall.
Around
Various subtypes can help people understand how CMML affects an individual.
Subtype 0, 1, or 2
One classification is by the number of blasts, or immature blood cells, in the bone marrow.
Most people have
In CMML, blast counts fall into one of
| Subtype | Blasts in bone marrow | Blasts in blood |
| CMML-0 | 5% | 2% |
| CMML-1 | 5% to 9% | 2% to 4% |
| CMML-2 | 10% to 19% | 5% to 19% |
The higher the level of blasts, the
MD-CMML vs. MP-CMML
Doctors may also refer to myelodysplastic CMML (MD-CMML) or myeloproliferative CMML (MP-CMML).
The difference depends on whether CMML is associated with faulty blood cell production or the overproduction of white blood cells. The types are based on white blood cell levels.
In MD-CMML, the white blood cell count is below
MP-CMML is when the white blood cell count is equal to or above 13,000 per microliter. The person will likely have a high blood cell count.
CMML vs. JMML
Doctors refer to CMML when it affects adults. In people under 18 years old, it is called juvenile myelomonocytic leukemia (JMML).
JMML usually appears before the age of 4 years old. It affects males two to three times more often than females.
CMML vs. AMML
In people with CMML, symptoms appear over time. It is also possible to have acute myelomonocytic leukemia (AMML), in which symptoms appear suddenly.
The symptoms of CMML vary between individuals and depend on their blood count.
People with MD-CMML
- anemia, leading to weakness, fatigue, and other symptoms
- spots or patches of purple bruising under the skin, known as petechiae or purpura
- frequent infections due to low levels of white blood cells
Symptoms of MP-CMML include:
- an enlarged liver
- an enlarged spleen, leading to discomfort just below the ribs
- fatigue
- night sweats
- bone pain
- loss of muscle mass
People with
Experts do not know precisely why CMML happens, but risk factors seem to include:
- being
60 years of age or older - being male
- previous treatment with chemotherapy
- genetic changes that happen during a person’s lifetime
CMML
Risk factors for JMML
JMML, which affects children, also appears to stem from genetic changes after birth. These changes are not inherited, and the person will not pass them on to their children.
However, children with other genetic features present from birth, such as Noonan’s syndrome, may be more likely to develop JMML.
To test for CMML, a doctor may recommend:
- blood tests
- bone marrow tests
- a biopsy
- chromosomal testing
- genetic testing
They will likely consider blood readings over at least
Treatment can help manage CMML and
Factors affecting the decision
- existing symptoms
- the risk of CMML worsening or developing into AML
- the person’s age
- overall health status
- the type of treatment available
- how treatment will affect the person’s quality of life
The doctor may discuss the
- drug treatment
- chemotherapy
- bone marrow transplant
- iron chelation therapy, in some cases
- supportive care, such as counseling
- treatment for symptoms such as anemia
For children with JMML, a stem cell transplant is the main treatment option.
The outlook for CMML will depend on the type and how it affects the individual. Factors that
In some cases, the risk is low, and the person can live with CMML without needing treatment.
However, some people have a high risk type. In
Some researchers suggest a person with high risk CMML may live on average
For children with JMML, around 50% of those who undergo hematopoietic stem cell transplant experience long-term remission. However, around 35% to 40% have a relapse, often within a year.
A person with low risk CMML may not need any treatment or lifestyle changes, although a doctor may recommend regular blood tests to monitor the condition.
A person with high risk CMML may need intensive treatment that will affect their daily life. However, some people who undergo treatment experience long-term remission.
Counseling can help anyone with CMML to manage the concerns and anxiety that can arise from living with a long-term condition.
CMML is a rare type of blood cancer. It usually affects older people. One form, JMML, can appear in young children.
The outlook varies widely, depending on the type of CMML and how it affects the individual. For some, it can become life threatening. Others, however, develop no symptoms or experience long-term remission.