What Are Myelodysplastic Syndromes (MDS)?

What Causes Myelodysplastic Syndromes?

The bone marrow in healthy people produces new, immature blood cells that mature over time. Myelodysplastic syndromes occur when something disrupts this process to prevent the blood cells from maturing. Most myelodysplastic syndromes do not have a known cause. However, certain risk factors are associated with these cancers, including:

• Older age: The majority of people diagnosed with myelodysplastic syndromes are older than 60.
• Radiation treatment or chemotherapy: Previous radiation therapy or chemotherapy for other types of cancer can increase a person’s risk of developing a myelodysplastic syndrome.
• Exposure to certain chemicals: Benzene and certain other chemicals have been linked to the development of myelodysplastic syndromes.

Types of Myelodysplastic Syndromes

The World Health Organization divides myelodysplastic syndromes into subtypes based on the type of blood cells (red cells, white cells and platelets) involved. Myelodysplastic syndrome subtypes include:

• Myelodysplastic syndromes with single-lineage dysplasia: In this MDS, either the white blood cells, red blood cells or platelets are low in number and appear abnormal under the microscope.
• Myelodysplastic syndromes with multilineage dysplasia: Two or three blood cell types are abnormal under the microscope.
• Myelodysplastic syndromes with ring sideroblasts: A low number of one or more blood cell type characterizes this MDS. Another characteristic of this subtype is the presence of ring sideroblasts, which are immature red blood cells with nuclei surrounded by rings of iron.
• Myelodysplastic syndromes with isolated del(5q) chromosome abnormality: This MDS subtype is characterized by low numbers of red blood cells along with a specific mutation in the cell DNA.
• Myelodysplastic syndromes with excess blasts: With this subtype, any of the three types of blood cells might be low and appear abnormal under a microscope. In addition, very immature blood cells (blasts) are present in the blood and bone marrow.
• Unclassifiable myelodysplastic syndrome: In the unclassifiable variety, reduced numbers of one or more types of mature blood cells are present that may appear abnormal under the microscope. In addition, some blood cells may appear normal but contain DNA changes associated with myelodysplastic syndromes.

Signs and Symptoms of Myelodysplastic Syndromes

People with a myelodysplastic syndrome might not show any signs and symptoms of disease at first.

As the disease progress, symptoms may include:

• Fatigue
• Shortness of breath
• Unusual paleness due to a low red blood cell count (anemia)
• Easy or unusual bruising or bleeding due to a low blood platelet count (thrombocytopenia)
• Tiny red spots just beneath the skin caused by bleeding (petechiae)
• Frequent infections due to a low white blood cell count (leukopenia)

Note that other cancers and illnesses can cause the above symptoms. Always inform your doctor if you have symptoms of disease.

How Are Myelodysplastic Syndromes Diagnosed?

Procedures and tests used in the diagnosis of CML include:

• Physical exam: If your doctor suspects you have a myelodysplastic syndrome, they will usually perform a physical exam and go over your medical history.
• Blood tests: A complete blood count (CBC) with differential test is used to measure the number of white blood cells, red blood cells and platelets in a blood sample. In addition to measuring the numbers of such cells, your doctor will look for any unusual changes in the cell size, shape and appearance.
• Bone marrow test (bone marrow aspiration and biopsy): During a bone marrow biopsy and aspiration, a thin needle is used to extract (aspirate) a small sample of bone marrow, typically from the back of the hipbone. Also, a small piece of bone with its marrow intact is removed for testing (biopsy).

In addition to standard testing, more specialized tests can done on your blood and bone marrow samples to identify cell characteristics that are helpful in determining the type of myelodysplastic syndrome you may have, your prognosis and the best treatment options.

How Are Myelodysplastic Syndromes Treated?

Treatment of myelodysplastic syndromes usually focuses on slowing the progression of the disease, relieving symptoms and preventing complications. When a person is diagnosed with a myelodysplastic syndrome but does not have any symptoms, delaying treatment may be recommended. In this case, your doctor may recommend monitoring the condition through regular exams and lab testing to see if the disease progresses.

Treatment options include:

Myelodysplastic Syndromes Prognosis

Some people with a MDS live for years and require little or no treatment. For others, their MDS is more aggressive and may develop into acute myeloid leukemia (AML), which is an aggressive, life-threatening cancer that requires more urgent treatment. About one third of people with MDS will eventually develop AML. Although AML is a serious illness, the disease is often treatable and even curable with chemotherapy with or without a bone marrow/stem cell transplant.