Key Points for This Section

Myelodysplastic syndromes are a group of diseases in which the bone marrow does not make enough healthy blood cells. There are several types of myelodysplastic syndromes. Age and past treatment with chemotherapy or radiation therapy affect the risk of developing a myelodysplastic syndrome. Possible signs of myelodysplastic syndrome include feeling tired and shortness of breath. Tests that examine the blood and bone marrow are used to detect (find) and diagnose myelodysplastic syndromes. Myelodysplastic syndromes are diagnosed based on certain changes in the blood cells and bone marrow. Certain factors affect prognosis (chance of recovery) and treatment options.

Myelodysplastic syndromes are a group of diseases in which the bone marrow does not make enough healthy blood cells.

Myelodysplastic syndromes are diseases of the blood and bone marrow. Normally, the bone marrow makes blood stem cells (immature cells) that develop into mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. The lymphoid stem cell develops into a white blood cell. The myeloid stem cell develops into one of three types of mature blood cells:

• Red blood cells that carry oxygen and other materials to all tissues of the body.
• White blood cells that fight infection and disease.
• Platelets that help prevent bleeding by causing blood clots to form.

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Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.

In myelodysplastic syndromes, the blood stem cells do not mature into healthy red blood cells, white blood cells, or platelets. The immature blood cells, called blasts, do not function normally and either die in the bone marrow or soon after they enter the blood. This leaves less room for healthy white blood cells, red blood cells, and platelets to develop in the bone marrow. When there are fewer blood cells, infection, anemia, or easy bleeding may occur.

There are several types of myelodysplastic syndromes.

Myelodysplastic syndromes have too few of one or more types of healthy blood cells in the bone marrow or blood. Myelodysplastic syndromes include the following diseases:

• Refractory anemia.
• Refractory anemia with ringed sideroblasts.
• Refractory anemia with excess blasts.
• Refractory anemia with excess blasts in transformation.
• Refractory cytopenia with multilineage dysplasia.
• Myelodysplastic syndrome associated with an isolated del(5q) chromosome abnormality.
• Unclassifiable myelodysplastic syndrome.

See the following PDQ summaries for information about other blood cell diseases:

• Myelodysplastic and Myeloproliferative Diseases Treatment ¹
• Chronic Myeloproliferative Disorders Treatment ²

Age and past treatment with chemotherapy or radiation therapy affect the risk of developing a myelodysplastic syndrome.

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get a disease; not having risk factors doesn’t mean that you will not get a disease. People who think they may be at risk should discuss this with their doctor. Risk factors for myelodysplastic syndromes include the following:

• Being male or white.
• Being older than 60 years.
• Past treatment with chemotherapy or radiation therapy.
• Being exposed to certain chemicals, including tobacco smoke, pesticides, and solvents such as benzene.
• Being exposed to heavy metals, such as mercury or lead.

Possible signs of myelodysplastic syndrome include feeling tired and shortness of breath.

Myelodysplastic syndromes often do not cause early symptoms and are sometimes found during a routine blood test. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• Shortness of breath.
• Weakness or feeling tired.
• Having skin that is paler than usual.
• Easy bruising or bleeding.
• Petechiae (flat, pinpoint spots under the skin caused by bleeding).
• Fever or frequent infections.

Tests that examine the blood and bone marrow are used to detect (find) and diagnose myelodysplastic syndromes.

The following tests and procedures may be used:

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Complete blood count (CBC) with differential: A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells and platelets.
  • The number and type of white blood cells.
  • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  • The portion of the blood sample made up of red blood cells.

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  Complete blood count (CBC). Blood is collected by inserting a needle into a vein and allowing the blood to flow into a tube. The blood sample is sent to the laboratory and the red blood cells, white blood cells, and platelets are counted. The CBC is used to test for, diagnose, and monitor many different conditions.

• Peripheral blood smear: A procedure in which a sample of blood is checked for changes in the number, type, shape, and size of blood cells and for too much iron in the red blood cells.
• Cytogenetic analysis: A test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes.
• Bone marrow aspiration and biopsy: The removal of bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for abnormal cells.

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  Bone marrow aspiration and biopsy. After a small area of skin is numbed, a Jamshidi needle (a long, hollow needle) is inserted into the patient’s hip bone. Samples of blood, bone, and bone marrow are removed for examination under a microscope.

Myelodysplastic syndromes are diagnosed based on certain changes in the blood cells and bone marrow.

• Refractory anemia: There are too few red blood cells in the blood and the patient has anemia. The number of white blood cells and platelets is normal.



• Refractory anemia with ringed sideroblasts: There are too few red blood cells in the blood and the patient has anemia. The red blood cells have too much iron. The number of white blood cells and platelets is normal.



• Refractory anemia with excess blasts: There are too few red blood cells in the blood and the patient has anemia. Five percent to 19% of the cells in the bone marrow are blasts and there are a normal number of blasts found in the blood. There also may be changes to the white blood cells and platelets. Refractory anemia with excess blasts may progress to acute myeloid leukemia. See the PDQ Adult Acute Myeloid Leukemia Treatment ³ summary for more information.



• Refractory anemia with excess blasts in transformation: There are too few red blood cells, white blood cells, and platelets in the blood and the patient has anemia. Twenty percent to 30% of the cells in the bone marrow are blasts and more than 5% of the cells in the blood are blasts. Refractory anemia with excess blasts in transformation is sometimes called acute myeloid leukemia.



• Refractory cytopenia with multilineage dysplasia: There are too few of at least two types of blood cells. Less than 5% of the cells in the bone marrow are blasts and less than 1% of the cells in the blood are blasts. If red blood cells are affected, they may have extra iron. Refractory cytopenia may progress to acute leukemia.



• Myelodysplastic syndrome associated with an isolated del(5q) chromosome abnormality: There are too few red blood cells in the blood and the patient has anemia. Less than 5% of the cells in the bone marrow and blood are blasts. There is a specific change in the chromosome.



• Unclassifiable myelodysplastic syndrome: There are too few of one type of blood cell in the blood. The number of blasts in the bone marrow and blood is normal, and the disease is not one of the other myelodysplastic syndromes.

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

The prognosis (chance of recovery) depends on the following:

• Whether the myelodysplastic syndrome occurred after chemotherapy or radiation therapy for another disease.
• The number of blast cells in the bone marrow.
• Whether one or more types of blood cells are affected.
• Certain changes in the chromosomes.

Treatment options depend on the following:

• Whether the myelodysplastic syndrome occurred after chemotherapy or radiation therapy for another disease.
• Whether the myelodysplastic syndrome has progressed after being treated.
• The age and general health of the patient.

Glossary Terms

Not normal. An abnormal lesion or growth may be cancerous, premalignant (likely to become cancer), or benign.

A rapidly progressing cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of white blood cells to be produced and enter the blood stream.

A quickly progressing disease in which too many immature white blood cells (not lymphocytes) are found in the blood and bone marrow. Also called AML, acute myelogenous leukemia, acute myeloblastic leukemia, acute nonlymphocytic leukemia, and ANLL.

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

A chemical that is used widely by the chemical industry, and is also found in tobacco smoke, vehicle emissions, and gasoline fumes. Exposure to benzene may increase the risk of developing leukemia.

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.

A mass of blood that forms when blood platelets, proteins, and cells stick together. When a blood clot is attached to the wall of a blood vessel, it is called a thrombus. When it moves through the bloodstream and blocks the flow of blood in another part of the body, it is called an embolus.

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

The removal of a small sample of bone marrow (usually from the hip) through a needle for examination under a microscope.

The removal of a sample of tissue from the bone marrow with a needle for examination under a microscope.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

Treatment with drugs that kill cancer cells.

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

CBC. A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called blood cell count and CBC.

The study of chromosomes and chromosomal abnormalities.

A reduction in the number of blood cells.

Cells that look abnormal under a microscope but are not cancer.

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.

Referring to lymphocytes, a type of white blood cell. Also refers to tissue in which lymphocytes develop.

A group of diseases in which the bone marrow does not make enough healthy blood cells. Also called preleukemia and smoldering leukemia.

Having to do with or resembling the bone marrow. May also refer to certain types of hematopoietic (blood-forming) cells found in the bone marrow. Sometimes used as a synonym for myelogenous; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.

A colorless, odorless gas. It is needed for animal and plant life. Oxygen that is breathed in enters the blood from the lungs and travels to the tissues.

A doctor who identifies diseases by studying cells and tissues under a microscope.

PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. Most of this information, and more specific information about PDQ, can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called Physician Data Query.

A procedure in which a sample of blood is viewed under a microscope to count different circulating blood cells (red blood cells, white blood cells, platelets, etc.) and see whether the cells look normal.

Any substance that is used to kill insects and other pests.

Pinpoint, unraised, round red spots under the skin caused by bleeding.

An exam of the body to check for general signs of disease.

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

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

In medicine, the course of a disease, such as cancer, as it becomes worse or spreads in the body.

A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called radiotherapy and irradiation.

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

In medicine, describes a disease or condition that does not respond to treatment.

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 liquid that is able to dissolve a solid.

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.

A group or layer of cells that work together to perform a specific function.

A plant with leaves that have high levels of the addictive chemical nicotine. The leaves may be smoked (in cigarettes, cigars, and pipes), applied to the gums (as dipping and chewing tobacco), or inhaled (as snuff). Tobacco leaves also contain many cancer-causing chemicals, and tobacco use and exposure to secondhand tobacco smoke have been linked to many types of cancer and other diseases. The scientific name is Nicotiana tabacum.

In medicine, the change that a normal cell undergoes as it becomes malignant.

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.