Chronic myelomonocytic leukemia (CMML)
- Is an uncommon blood cancer that has features of two other types of blood cancers. For this reason, the World Health Organization (WHO) classifies CMML as a mixed myelodysplastic/myeloproliferative disease.
- Affects approximately three in 100,000 individuals in the United States each year.
- Generally affects older adults.
- Is diagnosed in twice as many males than females Has been reported in only a small number of older children and younger adults.
What You Should Know
- Many individual factors influence treatment outcomes.
- Hematologists and oncologists are specialists who treat people who have CMML or other types of blood cancer.
What You Should Do
- Talk with your doctor about your diagnostic tests and what the results mean.
- Seek treatment in a cancer center where doctors are experienced in treating patients with leukemia.
- Ask your doctor whether a clinical trial is a good treatment option for you.
How Does CMML Develop?
CMML is considered a clonal disorder, which means that it starts with one or more changes (mutations) to the DNA of a stem cell in the bone marrow that multiplies uncontrollably. Stem cells form blood cells (white cells, red cells and platelets).
The change to the stem cell affects the normal development of a type of white cell called a monocyte. Monocytes arise from immature blood-forming cells called myeloblasts and myelocytes.
The myeloblasts and myelocytes accumulate in the marrow and other organs and interfere with normal production of monocytes and other types of blood cells, including red cells and platelets.
Monocytes make up about 5 percent to 10 percent of cells in normal blood. When they leave the blood and enter the tissue, they convert into macrophages. Macrophages, along with other white cells called neutrophils, are in charge of ingesting and killing microbes, or germs, in the blood.
If not treated, CMML can lead to:
- Low numbers of red cells that can no longer supply an adequate amount of oxygen, resulting in anemia
- The immune system's inability to guard against infection effectively because of a lack of neutrophils (a type of white cell), a condition called neutropenia
- Low numbers of platelets, which can cause bleeding and easy bruising with no apparent cause, a condition called thrombocytopenia
Doctors don't know why some cells become chronic myelomonocytic leukemia (CMML) cells and others don't. They've found few risk factors associated with the disease. You can't catch CMML from someone else.