Myelodysplastic syndrome (MDS) is a group of cancers. MDS begins when a single stem cell develops permanent genetic mutations. This abnormal cell makes copies of itself over and over again. These abnormal cells multiply, take up valuable space, and prevent healthy cells from growing normally inside your bone marrow.
Major health organizations like the National Institutes of Health (NIH), the American Society of Clinical Oncology (ASCO), and the World Health Organization (WHO) classify MDS as a blood cancer.
What is myelodysplastic syndrome (MDS)?
Myelodysplastic syndromes (MDS) are a group of blood cancers. They start inside your bone marrow. Bone marrow is the spongy center inside large bones. It works like a blood cell factory. Healthy bone marrow produces three main types of blood cells:
Red blood cells: Distribute oxygen and nutrients to all organs and tissue.
White blood cells: Protect your body from infections and illnesses.
Platelets: Help the wound healing process and make clots to stop cuts and wounds from bleeding.
In people with MDS, the blood stem cells do not mature the way they should. The bone marrow produces abnormal, poorly formed blood cells that break down too quickly. Because these defective cells die before they can do their jobs, you end up with low blood counts (cytopenias). This can make you feel very tired, cause frequent infections, or lead to easy bruising and bleeding.
Why some people call MDS "pre-leukemia" and why that term is misleading
In the past, doctors sometimes called MDS "pre-leukemia." While this term was common years ago, medical experts now avoid it because it can be confusing and misleading:
MDS is an active condition on its own: It is not just an early stage of another disease. MDS causes real symptoms, low blood counts, and medical complications that need careful attention and treatment.
Most cases do not become leukemia: While MDS carries a chance of turning into acute leukemia, many patients never develop it. Treating MDS means focusing directly on your current symptoms, blood counts, and overall health.
What causes MDS, and is it hereditary?
In most cases, doctors do not know the exact cause of MDS. It often develops over time. However, several risk factors can increase a person's chances of developing it:
Older age: The risk rises as people age, and most patients are diagnosed in their 70s or older.
Past cancer treatments: Some chemotherapies or radiation therapies given for earlier cancers can damage bone marrow stem cells years later (called secondary or therapy-related MDS).
Chemical exposures: Long-term exposure to industrial chemicals like benzene or tobacco smoke can harm bone marrow health.
MDS is almost always acquired, meaning the genetic changes happen during your lifetime and are not passed down to your children. In very rare cases, people are born with specific inherited conditions that increase their chances of developing bone marrow failure or MDS.
How is MDS different from other blood cancers?
Both MDS and AML start in the same blood-forming myeloid stem cells. Doctors tell them apart by measuring the percentage of young, immature blood cells—called blasts—in your bone marrow:
In healthy bone marrow, blasts make up less than 5% of all cells.
In MDS, blast counts usually range between 5% and 19%.
When blast levels reach 20% or higher, doctors classify the condition as AML.
Other common blood cancers develop in different parts of the immune system. For example, lymphomas usually begin in the lymph nodes, while multiple myeloma starts in antibody-making plasma cells. MDS specifically affects the bone marrow stem cells that create red blood cells, infection-fighting white blood cells, and platelets.
Lower-risk vs. higher-risk MDS
Because MDS affects every person differently, doctors use scoring systems like the IPSS-R (Revised International Prognostic Scoring System) to place the disease into risk categories. These scores depend on your blast count, the number of low blood counts you have, and any genetic changes found in your cells.
Lower-risk MDS
Main goal: Improve daily quality of life, treat anemia, reduce the need for blood transfusions, and relieve symptoms.
Treatment: Medications that stimulate blood cell production (growth factors), targeted therapies to boost hemoglobin, and close monitoring with regular blood tests.
Higher-risk MDS
Main goal: Slow down the disease, prevent it from turning into AML, and help patients live longer.
Treatment: Specialized medications called hypomethylating agents that slow abnormal cell growth, clinical trial treatments, chemotherapy, or stem cell transplantation.
Can MDS be cured?
Currently, the only known cure for MDS is an allogeneic stem cell transplant (also known as a bone marrow transplant).
During this procedure, high doses of chemotherapy clear out the abnormal stem cells in your bone marrow. Then, healthy blood stem cells from a matched donor are infused into your blood to rebuild a healthy immune and blood-making system.
Because stem cell transplants cause physical stress on the body, they carry significant risks. They are usually recommended for patients with higher-risk MDS who are healthy enough for the procedure and have a compatible donor. For patients who cannot have a transplant, modern treatments focus on keeping the disease stable, relieving symptoms, and improving long-term health.
Questions to ask your care team about your MDS diagnosis
Here are a few clear questions to help guide the conversation at your next doctor's appointment:
What subtype of MDS do I have, and what is my risk score (lower-risk or higher-risk)?
What was the percentage of blast cells found in my bone marrow biopsy?
Did my tests show any specific chromosome changes or gene mutations?
Is our treatment plan focused on improving my blood counts, slowing the disease, or getting ready for a transplant?
Would a stem cell transplant be an option for me now or in the future?
Are there any clinical trials that fit my specific type of MDS?
Which warning signs or symptoms mean I should call the clinic right away?
Sources
