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Types of Cancer > Leukemia > Myelodysplastic Syndromes (MDS) > Overview
Myelodysplastic Syndromes (MDS): The Basics
Eric T. Shinohara, MD, MSCI
Affiliation:
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: January 11, 2009
What is Myelodysplastic Syndrome (MDS)?
MDS is a diverse group of syndromes which are characterized by the atypical (dysplastic) or ineffective production of blood cells. These syndromes are considered to be malignant stem cell disorders. Stem cells are immature cells in the bone marrow that gradually mature to form the various components of blood. There are three main cell lines which form blood:
- Red blood cells (also known as erythrocytes), which carry inhaled oxygen from the lungs to other organs and carry carbon dioxide from the organs to the lungs to be exhaled.
- Platelets (also known as thrombocytes), which form clots.
- White blood cells (also known as leukocytes), which are comprised of granulocytes, lymphocytes, and monocytes, each of which has a different role in the immune system. Lymphocytes are made up of B and T lymphocytes.
In MDS, the stem cells do not mature properly and create immature cells in the blood, known as blasts MDS can potentially transform into more aggressive malignancies such as acute leukemia
Am I at Risk for Myelodysplastic Syndrome?
The exact incidence of MDS is not known, however, estimates suggest that there are approximately 10,000 cased of MDS in the United States annually. Studies based on a large Cancer Registry in the United States suggested that there were approximately 3.3 people diagnosed with MDS per 100,000 people between 2001 and 2004.
Aging is a major risk factor for developing MDS. Recent studies have suggested that the number of people who will develop MDS is about 0.5 out of 100,000 people for people younger than 50 years of age. However this risk gradually increases; 89 out of 100,000 people who are older than 80 will develop MDS. The average age at which people are diagnosed with MDS is around 65 years of age. It is rare to see MDS diagnosed in people younger than 50 years of age unless the person has been exposed to substances which are mutagenic or have certain types of medical conditions. These conditions include a variety of genetic diseases such as Down’s syndrome and neurofibromatosis type I. Additionally people with defects in their ability to repair DNA damage, such as those individuals with Ataxia telangiectasia or Xeroderma pigmentosum are at increased risk for MDS. Prior treatment with certain types of chemotherapies, which damage the DNA (alkylating agents, topoisomerase inhibitors), also increase the risk of developing MDS. Certain chemical exposures, such as pesticides, solvents (such as benzene) and tobacco smoke can also increase the risk of developing MDS. Men and Caucasians appear to be at a slightly higher risk for developing MDS.
Though rare, MDS can occur in children at an average age of 6. There are two types of MDS which occur in children, juvenile myelomonocytic leukemia and monosomy-7 syndrome, both of which present in a similar fashion. Children with either of these diseases can present with an increased white blood cell count with a decreased red blood cell count and platelet count. The spleen may be enlarged and the skin may be involved as well. There may also be an increase in antibody production (polyclonal gammopathy).
How can I prevent MDS?
There are not any specific preventative interventions which can prevent MDS. Many of the risk factors can not be avoided, such as aging. Generally, if someone has a malignancy requiring chemotherapy or radiation it is difficult to avoid using these agents without compromising the treatment of the malignancy. One can avoid exposure to known mutational substances such as pesticides, solvents, and tobacco smoke.