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What is myelodysplastic syndrome?
Myelodysplastic syndrome is a group of disorders caused by blood cells that are not well formed due to damaged bone marrow cells.
Patients with myelodysplastic syndrome (MDS) have low numbers of red blood cells, white blood cells and/or platelets.
About 13,000 new cases of myelodysplastic syndrome are diagnosed annually in the United States, and the number of new cases continues to increase as the country’s population ages, according to the American Cancer Society.
MDS previously had been called pre-leukemia; however, physicians now know more about MDS, and most patients do not go on to be diagnosed with leukemia. About one in three patients with MDS later are diagnosed with acute myeloid leukemia.
Risk factors and symptoms
Risk factors for MDS include:
• Older age;
• Prior receipt of chemotherapy or radiation;
• Exposure to certain chemicals, such as tobacco smoke, pesticides and industrial chemicals; and
• Exposure to heavy metals, such as lead and mercury.
Symptoms often are not apparent early in the disease course. However, they can develop over time.
Symptoms may include:
• Easy or unusual bruising or bleeding;
• Fatigue;
• Frequent infections;
• Petechiae;
• Shortness of breath; and
• Unusual paleness from anemia.
Types/subtypes
MDS with no known cause is considered primary MDS. Secondary MDS is when the cause is known.
Secondary MDS is most common among those who have previously undergone treatment for cancer. Patients diagnosed with secondary MDS are less likely to experience treatment response, whereas primary MDS is easier to treat.
There are several subtypes of MDS. They include:
• Refractory cytopenia with unilineage dysplasia — one blood cell type is low and appears abnormal under the microscope;
• Refractory anemia with ringed sideroblasts — red blood cell counts are low and existing red blood cells contain excess iron;
• Refractory cytopenia with multilineage dysplasia — two blood cell types are abnormal, and less than 1% of cells in the bloodstream are blasts;
• Refractory anemia with excess blasts (types 1 and 2) — for both types, any of the three blood cell types may be low and appear abnormal under a microscope. Immature blasts are seen in the blood;
• MDS, unclassified — an uncommon subtype in which one of the three types of blood cells are low, and either the white blood cells or platelets appear abnormal under a microscope; and
• MDS associated with isolated del(5q) chromosome abnormality — red blood cell counts are low and cells have a particular mutation in DNA.
Treatments
Common treatment regimens for MDS focus on slowing of disease progression, preventing complications from the disease and decreasing side effects from treatment.
Patients may undergo blood transfusions to replace blood cell counts and, in some cases, patients may undergo a bone marrow transplant.
Various medications can be used to increase the number of healthy blood cells in patients with MDS. They include:
• Growth factor medications, or artificial versions of substances found naturally in bone marrow. Certain growth factors increase red blood cells and decrease the need for blood transfusions. Other growth factor medications increase white blood cells, helping to prevent infections;
• Medications that improve quality of life and reduce the risk for AML;
• Medications that suppress the immune system; and
• Medications for MDS associated with isolated del(5q).
Areas of research
Researchers continue to examine the causes of and potential treatments for MDS.
Prior studies have helped investigators learn how alterations in DNA may cause normal bone marrow cells to transform into cancer.
Other research designed to evaluate how stromal cells affect MDS cells have indicated that, although these cells in MDS are not cancerous, they appear to play a role in causing these syndromes.
Studies are underway to identify new potential treatments. These may include chemotherapies with fewer side effects; targeted therapies to identify and attack cancer cells while causing little harm to normal cells; new drugs to help increase platelet counts; and refined approaches for stem cell transplants.
More information is available at these websites:
www.mayoclinic.org/diseases-conditions/myelodysplastic-syndromes/basics/causes/con-20027168
www.cancer.gov/types/myeloproliferative/patient/myelodysplastic-treatment-pdq#section/_1