Myelodysplastic syndromes

Other Names: MDS; myelodysplasia

Myelodysplastic syndromes (MDS) are a group of blood disorders characterized by abnormal development of blood cells within the bone marrow. People with MDS have abnormally low blood cell levels (low blood counts). 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 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.

Risk factors

• 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.

Types

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). See the PDQ Adult Acute Myeloid Leukemia Treatment summary for more information. 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).

Cause

Approximately 80% of people with MDS do not have an obvious exposure or cause for MDS. In these cases, the disorder is classified as "primary" or "idiopathic" MDS. The development of MDS involves a series of genetic changes in a hematopoietic stem cell. These changes alter normal cell growth and differentiation (development into different types of blood cells). This results in an accumulation of abnormal, immature cells in the bone marrow and the impaired creation of new blood cells. Genetic changes leading to the development of MDS may result from an inherited predisposition, or from damage to a cell's DNA ( a somatic mutation) caused by exposure to chemotherapy, radiation, viral infection, or certain chemicals (e.g., benzene). It is classified as "secondary" MDS when it is due to aggressive treatment of other cancers. It also occurs in heavily pre-treated people with autologous bone marrow transplants.

MDS sometimes runs in families. While the condition itself is not inherited, a person may inherit a predisposition to MDS due to a mutation in the GATA2 gene, TERC gene, or TERT gene.

Signs and symptoms

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).

Diagnosis

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.

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.

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.

Treatment

Three types of standard treatment are used: Supportive care

Supportive care is given to lessen the problems caused by the disease or its treatment. Supportive care may include the following:

Transfusion therapy Transfusion therapy (blood transfusion) is a method of giving red blood cells, white blood cells, or platelets to replace blood cells destroyed by disease or treatment. A red blood cell transfusion is given when the red blood cell count is low and signs or symptoms of anemia, such as shortness of breath or feeling very tired, occur. A platelet transfusion is usually given when the patient is bleeding, is having a procedure that may cause bleeding, or when the platelet count is very low.

Patients who receive many blood cell transfusions may have tissue and organ damage caused by the buildup of extra iron. These patients may be treated with iron chelation therapy to remove the extra iron from the blood.

Erythropoiesis-stimulating agents Erythropoiesis-stimulating agents (ESAs) may be given to increase the number of mature red blood cells made by the body and to lessen the effects of anemia. Sometimes granulocyte colony-stimulating factor (G-CSF) is given with ESAs to help the treatment work better.

Antibiotic therapy Antibiotics may be given to fight infection.

Drug therapy

• Lenalidomide

Patients with myelodysplastic syndrome associated with an isolated del(5q) chromosome abnormality who need frequent red blood cell transfusions may be treated with lenalidomide. Lenalidomide is used to lessen the need for red blood cell transfusions.

• Immunosuppressive therapy

Antithymocyte globulin (ATG) works to suppress or weaken the immune system. It is used to lessen the need for red blood cell transfusions.

• Azacitidine and decitabine

Azacitidine and decitabine are used to treat myelodysplastic syndromes by killing cells that are dividing rapidly. They also help genes that are involved in cell growth to work the way they should. Treatment with azacitidine and decitabine may slow the progression of myelodysplastic syndromes to acute myeloid leukemia.

• Chemotherapy used in acute myeloid leukemia (AML)

Patients with a myelodysplastic syndrome and a high number of blasts in their bone marrow have a high risk of acute leukemia. They may be treated with the same chemotherapy regimen used in patients with acute myeloid leukemia.

• Chemotherapy with stem cell transplant

Chemotherapy is given to kill cancer cells. Healthy cells, including blood-forming cells, are also destroyed by the cancer treatment. Stem cell transplant is a treatment to replace the blood-forming cells. Stem cells (immature blood cells) are removed from the blood or bone marrow of the patient or a donor and are frozen and stored. After the patient completes chemotherapy, the stored stem cells are thawed and given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the body's blood cells.

This treatment may not work as well in patients whose myelodysplastic syndrome was caused by past treatment for cancer.

NIH genetic and rare disease info

• NIH info on Myelodysplastic syndromes

Myelodysplastic syndromes is a rare disease.

Myelodysplastic syndromes Resources
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