General Information About Myelodysplastic Syndromes

Myelodysplastic syndromes are a group of cancers in which immature blood cells in the bone marrow do not mature or become healthy blood cells.

In a healthy person, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time.

A blood stem cell may become a lymphoid stem cell or a myeloid stem cell. A lymphoid stem cell becomes a white blood cell. A myeloid stem cell becomes one of three types of mature blood cells:

• Red blood cells that carry oxygen and other substances to all tissues of the body.
• Platelets that form blood clots to stop bleeding.
• Granulocytes, which are white blood cells that help fight infection and disease.

In a patient with a myelodysplastic syndrome, the blood stem cells (immature cells) do not become mature red blood cells, white blood cells, or platelets in the bone marrow. These immature blood cells, called blasts, do not work the way they should and either die in the bone marrow or soon after they go into the blood. This leaves less room for healthy white blood cells, red blood cells, and platelets to form in the bone marrow. When there are fewer healthy blood cells, infection, anemia, or easy bleeding may occur.

The different types of 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 ring sideroblasts: There are too few red blood cells in the blood and the patient has anemia. The red blood cells have too much iron inside the cell. 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. There also may be changes to the white blood cells and platelets. Refractory anemia with excess blasts may progress to acute myeloid leukemia (AML). For more information, see Acute Myeloid Leukemia Treatment.
• Refractory cytopenia with multilineage dysplasia: There are too few of at least two types of blood cells (red blood cells, platelets, or white 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 myeloid leukemia (AML).
• Refractory cytopenia with unilineage dysplasia: There are too few of one type of blood cell (red blood cells, platelets, or white blood cells). There are changes in 10% or more of two other 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.
• Unclassifiable myelodysplastic syndrome: The numbers of blasts in the bone marrow and blood are normal, and the disease is not one of the other myelodysplastic syndromes.
• 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.
• Chronic myelomonocytic leukemia (CMML): For more information, see Myelodysplastic/Myeloproliferative Neoplasms Treatment.

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

Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop myelodysplastic syndromes, and they will develop in people who don't have any known risk factors. Talk with your doctor if you think you may be at risk. Risk factors for myelodysplastic syndromes include the following:

• Past treatment with chemotherapy or radiation therapy for cancer.
• Being exposed to certain chemicals, including tobacco smoke, pesticides, fertilizers, and solvents such as benzene.
• Being exposed to heavy metals, such as mercury or lead.

The cause of myelodysplastic syndromes in most patients is not known.

Signs and symptoms of a myelodysplastic syndrome include shortness of breath and feeling tired.

Myelodysplastic syndromes often do not cause early signs or symptoms. They may be found during a routine blood test. Signs and symptoms may be caused by myelodysplastic syndromes or by other conditions. Check with your doctor if you have any of the following:

• 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).

Tests that examine the blood and bone marrow are used to diagnose myelodysplastic syndromes.

In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform the following tests and procedures:

• 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.
  
• 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 laboratory test in which the chromosomes of cells in a sample of bone marrow or blood are counted and checked for any changes, such as broken, missing, rearranged, or extra chromosomes. Changes in certain chromosomes may be a sign of cancer. Cytogenetic analysis is used to help diagnose cancer, plan treatment, or find out how well treatment is working.
• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances, such as vitamin B12 and folate, released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease.
• 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.

  The following tests may be done on the sample of tissue that is removed:

  • Immunocytochemistry: A laboratory test that uses antibodies to check for certain antigens (markers) in a sample of a patient’s bone marrow. The antibodies are usually linked to an enzyme or a fluorescent dye. After the antibodies bind to the antigen in the sample of the patient’s cells, the enzyme or dye is activated, and the antigen can then be seen under a microscope. This type of test is used to help diagnose cancer and to tell the difference between myelodysplastic syndromes, leukemia, and other conditions.
  • Immunophenotyping: A laboratory test that uses antibodies to identify cancer cells based on the types of antigens or markers on the surface of the cells. This test is used to help diagnose specific types of leukemia and other blood disorders.
  • Flow cytometry: A laboratory test that measures the number of cells in a sample, the percentage of live cells in a sample, and certain characteristics of the cells, such as size, shape, and the presence of tumor (or other) markers on the cell surface. The cells from a sample of a patient’s blood, bone marrow, or other tissue are stained with a fluorescent dye, placed in a fluid, and then passed one at a time through a beam of light. The test results are based on how the cells that were stained with the fluorescent dye react to the beam of light. This test is used to help diagnose and manage certain types of cancers, such as leukemia and lymphoma.
  • FISH (fluorescence in situ hybridization): A laboratory test used to look at and count genes or chromosomes in cells and tissues. Pieces of DNA that contain fluorescent dyes are made in the laboratory and added to a sample of a patient’s cells or tissues. When these dyed pieces of DNA attach to certain genes or areas of chromosomes in the sample, they light up when viewed under a fluorescent microscope. The FISH test is used to help diagnose cancer and help plan treatment.

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

The prognosis and treatment options depend on the following:

• The number of blast cells in the bone marrow.
• Whether one or more types of blood cells are affected.
• Whether the patient has signs or symptoms of anemia, bleeding, or infection.
• Whether the patient has a low or high risk of leukemia.
• Certain changes in the chromosomes.
• Whether the myelodysplastic syndrome occurred after chemotherapy or radiation therapy for cancer.
• The patient's age and general health.