Myelodysplastic Syndromes - MDS: Introduction

Approved by the Cancer.Net Editorial Board, 12/2017

ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Myelodysplastic Syndromes (MDS). Use the menu to see other pages. Think of that menu as a roadmap for this complete guide.

About the blood and bone marrow

The bone marrow is the soft, spongy tissue found in the center of large bones that stores immature cells called stem cells. Stem cells usually mature into white blood cells, red blood cells, and platelets during a process called hematopoiesis. In the body, white blood cells fight infections, red blood cells carry oxygen throughout the body, and platelets help the blood to clot.

About myelodysplastic syndromes

Myelodysplastic syndromes, also known as MDS, are a group of blood and bone marrow disorders. MDS is considered a type of cancer. In MDS, stem cells do not mature as expected. This causes an increase in the number of immature cells, called blasts, and abnormally developed cells, called dysplastic cells. Also, the number of healthy mature cells in the blood decreases, causing the bone marrow to not work well or to stop working. This means that there are fewer healthy red blood cells, white blood cells, and/or platelets. The numbers of blood cells are often called blood cell counts (see Diagnosis).

Because of the decrease in healthy cells, people with MDS often have anemia, which is a low red blood cell count. They may also have neutropenia, which is a low white blood cell count, and thrombocytopenia, which is a low platelet count. In addition, dysplastic white blood cells and platelets, in particular, may not work correctly. Also, the chromosomes, or long strands of genes, in the bone marrow cells may be abnormal. Sometimes, the numbers of blood cells can be normal, but the blood and bone marrow cells are still abnormal.

There are several subtypes of MDS. Some subtypes of MDS may eventually turn into acute myeloid leukemia (AML). AML is a cancer of the blood in which immature cells called blasts increase and grow uncontrollably.

Looking for More of an Introduction?

If you would like more of an introduction, explore this related item. Please note that this link will take you to another section on Cancer.Net:

  • ASCO Answers Fact Sheet: Read a 1-page fact sheet that offers an introduction to MDS. This fact sheet is available as a PDF, so it is easy to print

The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with MDS and general survival rates. Use the menu to choose a different section to read in this guide.