MDS subtypes

Doctors use information about how the MDS is affecting your blood cells and bone marrow and if there are any abnormal changes to your chromosomes to describe which type of MDS you have. This is called the subtype. For example:

• In some types of MDS your blood will have a high number of blast cells – these are white blood cells that haven’t developed properly. 
• In some types, your blood cells or chromosomes may be abnormal in some way.

Knowing the subtype helps your doctor to plan the best way to treat your MDS and understand the likely course of your disease. 

The system doctors use to describe the different types of MDS is called a classification system. The 2 main classification systems are:

The name of the different MDS subtypes can sound confusing and they can be hard to understand. 

The words describe the effect on blood cells or bone marrow. For example: 

• Mutation: When a gene is changed, so it is abnormal 
• Deletion (del): When part or all of a chromosome is missing 
• Dysplasia: When there are abnormal cells 
• Single lineage dysplasia: Only 1 cell type is abnormal Multi-lineage dysplasia: More than one cell type is abnormal 
• Blasts: Blood cells in the earliest stage of development that are abnormal. With MDS there can be too many of these cells in the blood or bone marrow, which can lead to a lower than normal number of healthy blood cells

The numbers, such as 5q, SF3B1, refer to the chromosome or gene affected. 

Your doctor will explain which type of MDS you have. If you are confused or have more questions, don't be afraid to ask your doctor or specialist nurse.

High-risk or low-risk MDS refers to your chance of developing acute myeloid leukaemia (AML) and how long you are expected to live. Most patients do not go on to develop leukaemia, but in some people, MDS will develop into a type of cancer of the blood called acute myeloid leukaemia (AML). The risk of this happening depends on the type of MDS you have.

Your doctor may use a prognostic scoring system, such as the Revised International Prognostic Scoring System (IPSS-R) to help them to decide if your MDS is low risk or high risk. The treatment of low-risk and high-risk disease is often different. 

The IPSS-R is based on the following factors: 

• The number of cell types that are low in your blood (cytopenia) 
• The amount of blasts (immature blood cells) in your blood and bone marrow 
• Any chromosome changes (cytogenetics) 

Each factor gets a score. Together, the scores tell which risk group you fall into:

1. Very low risk 
2. Low risk 
3. Intermediate risk 
4. High risk 
5. Very high risk 

Ask your doctor and nurse to explain prognostic scoring. It can be confusing. You can also call our Support Line on 1800 200 700 or visit a Daffodil Centre for advice.