Myelodysplastic syndrome (MDS) at a glance
- Myelodysplastic syndromes (MDS) are a group disorders in which blood-forming cells in the bone marrow do not mature or become healthy blood cells.
- The different types of MDS are characterized by their specific changes in the blood cells and bone marrow.
- MDS often does not cause early symptoms, and many cases are diagnosed by a blood test given for unrelated purposes. When symptoms are present they can include shortness of breath, weakness, bruising and tiredness.
- Treatments for MDS are as varied as the MDS clinical picture. They may include medicine to increase the red blood cell number, transfusions, chemotherapy and, in some cases, a bone marrow transplant.
What is myelodysplastic syndrome?
Myelodysplastic syndromes, sometimes called MDS, are a group of blood disorders caused by poorly formed or functioning blood cells.
Bone marrow is spongy tissue inside the central bones and this marrow contains stem cells, which are the cells that develop a body’s red cells, white cells and platelets. Red blood cells carry oxygen in the body, white blood cells resist infection and platelets are an essential part of the coagulation system. In patients with MDS, one or a combination of the different blood cells are not regulated in their development. This process is unstable, leading to too few or too many of these cells (the levels of which can change over time).
The most common feature of MDS is anemia, which is fewer than normal red cells. There are several types of MDS, based on how blood cell formation is affected.
Acute myeloid leukemia (AML)
In the past, this was sometimes referred to as preleukemia, or smoldering leukemia. MDS can progress to a rapidly growing immature white cell process called acute myeloid leukemia (AML).
The potential for this type of transition in MDS is one reason for ongoing observation.
Myelodysplastic syndrome symptoms
Myelodysplastic syndrome symptoms relate to the severity of blood cell (red, white and platelet) production impairment. A hematologist observes and provides appropriate treatment for any combination of cell abnormalities. A low red blood cell count is called anemia. A low white blood cell count is called leukopenia. A low blood platelet count is called thrombocytopenia.
Myelodysplastic syndrome symptoms may include:
- Shortness of breath.
- Feeling tired or weak.
- Skin that is paler than usual.
- Easy or unusual bruising or bleeding.
- Pinpoint red spots under the skin caused by bleeding.
- Fever or frequent infections.
Causes and risk factors of MDS
In most cases, the cause of myelodysplastic syndrome isn’t known. Our understanding is growing about how DNA changes bone marrow cells that can cause MDS to develop. DNA studies are now part of MDS evaluations. This information has led to improved characterization of MDS and subtypes. Hematologist can now offer improved insight into what patients may expect during the course of care.
Some cases of MDS are associated with risk factors, including:
- Age, as MDS develops more in people age 60 or older.
- Prior radiation treatment or chemotherapy.
- Exposure to certain chemicals including tobacco smoke, pesticides and industrial chemicals.
- Exposure to heavy metals such as lead and mercury.
- Genetic factors.
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Types of MDS cancers
The World Health Organization divides myelodysplastic syndromes into subtypes based on the type of blood cells – red cells, white cells and platelets – involved. They are then divided into subtypes by looking at the number of low blood cells (call cytopenia), the count of immature cells (blasts), and how abnormal they appear under a microscope.
- MDS with single dysplasia occurs when the level of one type of blood cell is low, but the other two types of blood cells’ levels are normal. Most commonly, red blood cell levels are low, while white blood cell and platelet levels are healthy. This is called refractory anemia.
- MDS with ring sideroblasts results from impaired utilization of iron by developing red cells. The number of white blood cells and platelets is normal.
- MDS with excess blasts occurs when there are too few red blood cells and 5% to 19% of the cells in the bone marrow are blasts (blood stem cells). There also may be changes to the white blood cells and platelets.
- MDS with multilineage dysplasia results from too few of at least two types of blood cells (red blood cells, white blood cells or platelets).
- Unclassifiable myelodysplastic syndrome is a rare form of MDS where the number of red blood cells, white blood cells or platelet cells is low, but the blood and bone marrow tests do not fit any other type of MDS.
- Myelodysplastic syndrome associated with an isolated del(5q) chromosome abnormality occurs when the bone marrow contains cells in which part of chromosome 5 is missing. Additionally, red blood cell levels are low but white blood cell levels are normal. Platelet levels may be increased.
- Chronic myelomonocytic leukemia (CMML) begins in bone-marrow blood forming cells. CMML has characteristics of MDS and myeloproliferative neoplasma, which is excessive and abnormal bone marrow growth.
The first step in diagnosing MDS is a blood test to review the levels of white cells, red cells and platelets. Moreover, our hematologists, specialists in diseases of the blood and their treatment, can also review blood cells’ shape and other abnormalities.
If blood test results indicate MDS, further tests can determine the type and extent of the disease. One such test is a bone marrow aspiration and biopsy, which includes removal of bone marrow, blood and a small piece of bone from the hip, typically all at the same time.
Other procedures, including genetic or chromosomal tests and blood chemistry studies, may also be used to help with diagnosis.
After identifying which type of MDS a patient has, our multidisciplinary team will then determine whether it is a primary or secondary myelodysplastic syndrome. Primary myelodysplastic syndromes make up about 80% of all MDS cases, forming spontaneously without apparent risk factors.
Secondary MDS can result from DNA damage occurring in previous radiation or chemotherapy. Secondary MDS is typically associated with more complex chromosomal abnormalities and may require more intricate forms of treatment.
Myelodysplastic syndrome treatment
Treatment is based on the type of MDS, the patient’s risks for MDS and other factors, such as the patient’s age, overall health and medical history. There is no cure for MDS, and the goal for treatment is to relieve symptoms and avoid side effects. We often perform more than one type of treatment.
Medication can be used to alleviate symptoms, such as anemia and infections, or to boost the number of red blood cells.
Blood transfusions can replace white or red blood cells or platelets.
Bone marrow transplant is often the first choice for younger, relatively healthy patients if a matched donor is found. Unfortunately, many people with MDS are older or in poor health and therefore might not be good candidates.
Chemotherapy drugs can often improve blood counts, reduce a patient’s dependence on transfusions and improve quality of life.
Risks of treatment
Our doctors will discuss the risks and side effects of each treatment with the individual patient and his or her family.
Chemotherapy carries additional risks related to the progression of the disease. Chemotherapy side effects include fatigue, nausea, hair loss, infection and poor appetite. The side effects generally fade away after treatment ends.