Key Points for This Section

Chronic myelomonocytic leukemia is a disease in which too many myelocytes and monocytes (immature white blood cells) are made in the bone marrow. Older age and being male increase the risk of developing chronic myelomonocytic leukemia. Possible signs of chronic myelomonocytic leukemia include fever, feeling very tired, and weight loss. Certain factors affect prognosis (chance of recovery) and treatment options.

Chronic myelomonocytic leukemia is a disease in which too many myelocytes and monocytes (immature white blood cells) are made in the bone marrow.

In CMML, the body tells too many blood stem cells to develop into two types of white blood cells called myelocytes and monocytes. Some of these blood stem cells never become mature white blood cells. These immature white blood cells are called blasts. Over time, the myelocytes, monocytes, and blasts crowd out the red blood cells and platelets in the bone marrow. When this happens, infection, anemia, or easy bleeding may occur.

Older age and being male increase the risk of developing chronic myelomonocytic leukemia.

Anything that increases your chance of getting a disease is called a risk factor. Possible risk factors for CMML include the following:

• Older age.
• Being male.
• Being exposed to certain substances at work or in the environment.
• Being exposed to radiation.
• Past treatment with certain anticancer drugs.

Possible signs of chronic myelomonocytic leukemia include fever, feeling very tired, and weight loss.

These and other symptoms may be caused by CMML. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• Fever for no known reason.
• Infection.
• Feeling very tired.
• Weight loss for no known reason.
• Easy bruising or bleeding.
• Pain or a feeling of fullness below the ribs.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options for CMML depend on the following:

• The number of white blood cells or platelets in the blood or bone marrow.
• Whether the patient is anemic.
• The amount of blasts in the blood or bone marrow.
• The amount of hemoglobin in red blood cells.
• Whether there are certain changes in the chromosomes.

Glossary Terms

A condition in which the number of red blood cells is below normal.

An immature blood cell.

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.

Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.

A slowly progressing type of myelodysplastic/myeloproliferative disease in which too many myelomonocytes (a type of white blood cell) are in the bone marrow, crowding out other normal blood cells, such as other white blood cells, red blood cells, and platelets. Also called chronic myelomonocytic leukemia.

Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.

An increase in body temperature above normal (98.6 degrees F), usually caused by disease.

The substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

A type of white blood cell.

A type of blood cell that helps prevent bleeding by causing blood clots to form. Also called thrombocyte.

The likely outcome or course of a disease; the chance of recovery or recurrence.

Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).

A cell that carries oxygen to all parts of the body. Also called erythrocyte and RBC.

Something that may increase the chance of developing a disease. Some examples of risk factors for cancer include age, a family history of certain cancers, use of tobacco products, certain eating habits, obesity, lack of exercise, exposure to radiation or other cancer-causing agents, and certain genetic changes.

A cell from which other types of cells develop. For example, blood cells develop from blood-forming stem cells.

An indication that a person has a condition or disease. Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.

Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infections and other diseases. Also called WBC.