Myelodysplastic syndromes are a group of disorders caused by poorly formed blood cells or ones that don't work properly. Myelodysplastic syndromes result from something amiss in the spongy material inside your bones where blood cells are made (bone marrow).
Treatment for myelodysplastic syndromes usually focuses on reducing or preventing complications of the disease and its treatments. In some cases, treatment might involve chemotherapy or a bone marrow transplant.
Bone marrow is found in the middle of certain bones. It is made up of blood-forming cells, fat cells, and supporting tissues. A small fraction of the blood-forming cells are blood stem cells. Stem cells are needed to make new blood cells.
There are 3 main types of blood cells: red blood cells, white blood cells, and platelets.
Red blood cells pick up oxygen in the lungs and carry it to the rest of the body. These cells also bring carbon dioxide back to the lungs. Having too few red blood cells is called anemia. It can make a person feel tired and weak and look pale. Severe anemia can cause shortness of breath.
White blood cells (also known as leukocytes) are important in defending the body against infection. There are different types of white blood cells:
Platelets are thought of as a type of blood cell, but they are actually small pieces of a cell. They start as a large cell in the bone marrow called the megakaryocyte. Pieces of this cell break off and enter the bloodstream as platelets. You need platelets for your blood to clot. They plug up damaged areas of blood vessels caused by cuts or bruises. A shortage of platelets, called thrombocytopenia, can result in abnormal bleeding or bruising.
But in MDS, your bone marrow doesn't make enough of these healthy blood cells. Instead, it makes abnormal cells that aren't fully developed (immature).
As the condition develops, your bone marrow gets gradually taken over by the immature blood cells, which don't work properly.
They squeeze out the healthy ones, making the number of cells that manage to get into the bloodstream lower and lower.
The condition can develop slowly (indolent) or quickly (aggressive), and in some people it can develop into a type of leukaemia called acute myeloid leukaemia (AML).
There are many subtypes of Myelodysplastic Syndromes (MDS). For each patient, the subtype is determined using the results of the blood and bone marrow tests your MDS physician will perform. There are many classification systems.
Generally MDS can be divided into the following subtypes:
A main feature of myelodysplastic syndromes (MDS) is that they cause low blood cell counts. Sometimes this is found on blood tests, even before symptoms appear. In other cases, symptoms related to shortages of one or more types of blood cells (cytopenias) are the first sign of MDS:
People with MDS may experience the following symptoms or signs. Sometimes, people with MDS do not have any of these changes. Or, the cause of a symptom may be a different medical condition that is not MDS.
In a healthy person, bone marrow makes new, immature blood cells that mature over time. Myelodysplastic syndromes occur when something disrupts this process so that the blood cells don't mature.
Instead of developing normally, the blood cells die in the bone marrow or just after entering the bloodstream. Over time, there are more immature, defective cells than healthy ones, leading to problems such as fatigue caused by anemia, infections caused by leukopenia, and bleeding caused by thrombocytopenia.
Some myelodysplastic syndromes have no known cause. Others are caused by exposure to cancer treatments, such as chemotherapy and radiation, or to toxic chemicals, such as tobacco, benzene and pesticides, or to heavy metals, such as lead.
A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, you can change. Others, like your age or family history, can’t be changed.
But having a risk factor, or even several, does not always mean that a person will get the disease, and many people get cancer without having any known risk factors.
There are several known risk factors for myelodysplastic syndromes (MDS).
Older age: Most people with myelodysplastic syndromes are older than 60.
Treatment with chemotherapy or radiation: Chemotherapy or radiation therapy, both of which are commonly used to treat cancer, can increase your risk of myelodysplastic syndromes.
Exposure to certain chemicals: Chemicals linked to myelodysplastic syndromes include tobacco smoke, pesticides and industrial chemicals, such as benzene.
Exposure to heavy metals: Heavy metals linked to myelodysplastic syndromes include lead and mercury.
Gender: men are more prone to MDS than women.
Smoking: smoking increases risk of MDS.
Genetic diseases: people at increased risk of MDS include those with:
Complications of myelodysplastic syndromes include:
Anemia: Reduced numbers of red blood cells can cause anemia, which can make you feel tired.
Recurrent infections: Having too few white blood cells increases your risk of serious infections.
Bleeding that won't stop: Lacking platelets in your blood to stop bleeding can lead to excessive bleeding.
Increased risk of cancer: Some people with myelodysplastic syndromes might eventually develop a cancer of the blood cells (leukemia).
MDS is diagnosed using information gathered from a number of different tests. These include a physical examination, blood tests, a bone marrow biopsy, x-rays and other more specialised tests.
Full blood count
The first step in the diagnosis is a simple blood test called a full blood count (FBC) or complete blood count (CBC). This involves a sample of blood from a vein in your arm being sent to the laboratory for investigation. Most people with MDS have a low red cell and platelet count. Many of the white blood cells may be abnormal leukemic blast cells and the presence of these blast cells suggests you have MDS.
Bone marrow examination
If the results of your blood tests suggest that you might have MDS, a bone marrow biopsy may be required to help confirm the diagnosis. A bone marrow biopsy involves taking a sample of bone marrow, usually from the back of the hip bone and sending it to the laboratory for examination under the microscope. The bone marrow biopsy may be done in the haematologist’s rooms, clinic or day procedure centre and is usually performed under local anaesthesia with sedation given either by tablet or through a small drip in your arm.
The sample of bone marrow is examined in the laboratory to determine the number and type of cells present and the amount of haemopoiesis (blood forming) activity taking place there. Although the blood counts are low, in the majority of cases of MDS the bone marrow is very active but with increased numbers of immature cells that are abnormal in shape, appearance and size. In addition, blood cell production is usually found to be very inefficient; this is referred to as ineffective haematopoiesis. The percentage of blast cells (the abnormal stem cells) seen in the bone marrow (and sometimes in the blood) gives a guide to the severity of the MDS.
The results of this bone marrow test may take a few days to be finalised.
Once the diagnosis of MDS is made, blood and bone marrow cells are examined further using special laboratory tests. These include immunophenotyping and cytogenetic tests. These tests provide more information about the exact type of disease you have, the likely course of your disease and the best way to treat it.
These may be conducted to provide information on your general health and how your vital organs are functioning. These include a combination of further blood tests and imaging tests (x-rays, scans and ECG). These results will provide a baseline of your disease and general health which will be compared with later results to assess how well you are progressing and responding to treatment.
Treatment for myelodysplastic syndromes most often targets slowing disease progression, managing symptoms, such as fatigue, and preventing bleeding and infections.
If you have no symptoms, your doctor might recommend watchful waiting with regular exams and lab tests to see if the disease progresses.
Research on myelodysplastic syndromes is ongoing. Ask your doctor about clinical trials for which you might be eligible.
Blood transfusions can be used to replace red blood cells, white blood cells or platelets in people with myelodysplastic syndromes.
Treatment for myelodysplastic syndromes might include medications that:
Bone marrow transplant
During a bone marrow transplant, also known as a stem cell transplant, high doses of chemotherapy drugs are used to clear out the defective blood cells from your bone marrow. Then the abnormal bone marrow stem cells are replaced with healthy, donated cells (allogeneic transplant).
Newer techniques use less-toxic chemotherapy before the transplant than did older ones. However, bone marrow transplants carry a significant risk of side effects. For this reason, few people with myelodysplastic syndromes are candidates for bone marrow stem cell transplant.