The term myelodysplastic syndromes (MDS) encompasses a type of bone marrow cancer in which the immature blood cells are unable to mature into healthy, adult blood cells.
This type of disease is usually detected in the rudimentary blood tests that we do to check that everything is going well because, in the beginning, the symptoms are not noticeable. That is why it is so important to perform analytics periodically.
The main symptoms that patients notice, once this disease has progressed, are the problems to breathe and the feeling of continuous tiredness.
The life expectancy of people suffering from MDS is very heterogeneous since it depends on the type of specific syndrome as well as other factors such as age or the substances to which they have been exposed in their life (chemical substances, heavy metals …).
Characteristics of myelodysplastic syndromes
To understand what myelodysplastic syndromes are, we must first know what the normal functioning of the bone marrow and blood cells is.
In healthy people, the bone marrow contains stem cells that can mature into blood cells, among others.
A blood stem cell can be of two types: a lymphoid stem cell or a myeloid stem cell. The lymphocytes mature in white blood cells whereas the myeloid stem cells can mature into one of the following types of blood cells:
- Red blood cells, which carry oxygen and nutrients to all tissues of the body.
- Platelets, which form a barrier (blood clots) to stop bleeding.
- White blood cells, which are part of the immune system and fight against infections and diseases.
The myelodysplastic syndrome is characterized because the myeloid stem cells are not able to mature in adult blood cells such as red blood cells, platelets and white blood cells and remain in an intermediate state of maturity, forming cells called blast cells.
The blast cells do not work as they should and they have a very short life, dying shortly after leaving the blood or in the same bone marrow, leaving little space for healthy cells that have been able to mature.
When the level of healthy blood cells falls drastically the person can suffer problems such as infections, anemia or frequent bleeding.
Signs and symptoms
Normally the symptoms of these syndromes are not noticed until the person has been with the disease for some time. Although each syndrome has different characteristics, they all share the following symptoms:
- Respiration problems.
- Weakness and fatigue.
- Paleness of skin (more than usual).
- Bruising and bleeding easily.
- Petechiae (spots on the skin that form when a hemorrhage occurs near the skin, but there is no wound through which blood can leak).
Types of myelodysplastic syndromes
The myelodysplastic syndromes are differentiated in the type of blood cell affected, so it is necessary to make precise blood tests to diagnose which specific type of myelodysplastic syndrome the patient suffers from.
The WHO (World Health Organization) differentiates the following syndromes:
- Refractory cytopenia with unilinear dysplasia (RCUD)
- Refractory anemia with ringed sideroblasts (RARS)
- Refractory cytopenia with multilineage dysplasia (RCMD)
- Refractory anemia with excess blasts-1 (RAEB-1)
- Refractory anemia with excess blasts-2 (RAEB-2)
- Unclassified myelodysplastic syndrome (MDS-U)
- Myelodysplastic syndrome associated with 5q deletion isolated.
Refractory cytopenia with unilinear dysplasia (RCUD)
Between 5 and 10% of patients suffering from myelodysplastic syndrome have a refractory cytopenia with unilinear dysplasia (RCUD).
The term RCUD encompasses a group of myelodysplastic syndromes in which only one type of blood cell is affected, while the other types remain normal. Also, not all blood cells of that type are affected, there are only problems in about 10% of the cells (dysplasia).
The following syndromes are included in this group:
- Refractory anemia (RA). RA is the most common type of RCUD, in this syndrome the affected blood cells are red blood cells, whose level in the blood is very low. The levels of the rest of blood cells and blastocysts are normal.
- Refractory neutropenia (RN)
- Refractory thrombocytopenia (RT)
Sometimes an RCUD can degenerate and become an acute myeloid leukemia, but it is not very frequent, normally patients with RCUD live for a long time and with a good quality of life.
Refractory anemia with ringed sideroblasts (RARS)
Between 10 and 15% of patients suffering from some myelodysplastic syndrome have refractory anemia with ringed sideroblasts (RARS).
This syndrome is very similar to refractory anemia, only red blood cells are affected. With the difference that in the immature red blood cells present in the RARS iron deposits can be observed around their nuclei, forming rings, so these cells are called ring sideroblasts.
In rare cases, RARS can degenerate into leukemia and it is normal for patients to live for a prolonged period of time.
Refractory cytopenia with multilineage dysplasia (RCMD)
This is the most common type of myelodysplastic syndrome, around 40% of patients with DS have a refractory cytopenia with multilineage dysplasia (RCMD).
The RCMD are characterized because at least two types of blood cells are affected, while the others are intact, and the number of blasts in both the blood and the marrow is normal.
In approximately 10% of the cases of patients with RCMD this ends up degenerating a leukemia. Unlike the two previous myelodysplastic syndromes, patients suffering from this syndrome have a short life expectancy, it is estimated that about half of patients die within 2 years after the diagnosis was established.
Refractory anemia with excess blasts-1 (RAEB-1)
This type of anemia is characterized because one or more types of blood cells are affected, which are found at very low levels in both the blood and the bone marrow.
In addition, there is an excess of blasts in the bone marrow, although they usually represent less than 10% of blood cells. The blast cells do not contain Auer sticks, which is a waste material.
Many patients with RAEB-1 end up developing acute myeloid leukemia, approximately 25%. The life expectancy of people suffering from RAEB-1 is approximately 2 years, as are those who suffer RCMD.
Refractory anemia with excess blasts-2 (RAEB-2)
RAEB-2 is very similar to RAEB-1, with the difference that in the first the number of blastocysts in the bone marrow is greater, being able to make up to 20% of the blood cells of the marrow.
They also differ in that there is an excess of blastocysts also in the blood, where between 5 and 19% of white blood cells have not been able to mature and have remained blastocysts. These blast cells may contain Auer rods.
The probability that a patient with RAEB-2 will end up developing acute myeloid leukemia is very high, approximately 50%. Therefore, patients with this syndrome have a poor prognosis.
Myelodysplastic syndrome associated with del (5q) isolated
The main characteristic of this myelodysplastic syndrome is that the chromosomes of the blood stem cells lack chromosome 5 and this leads to their development in an abnormal way.
Red blood cell levels are a little low and patients may have anemia, while white blood cell levels are normal and platelet levels can even be increased.
Patients with this syndrome do not usually develop leukemia and have a favorable prognosis with a long life expectancy.
Unclassified myelodysplastic syndrome (MDS-U)
It’s syndrome is the least common of all myelodysplastic syndromes. MDS-U is diagnosed as any syndrome that meets the criteria of an MDS, with abnormal blood cells, but does not meet the criteria for any particular type of MDS.
Within this group, patients with very different characteristics are included, which makes it difficult to establish a general prognosis.
There are factors that can increase the likelihood of having a myelodysplastic disorder, such as the following:
- Having had treatment with chemotherapy or radiotherapy, for example, to treat cancer.
- Have been exposed to certain chemical compounds such as pesticides, fertilizers and / or solvents, for example, at work.
- Be a smoker
- Have been exposed to heavy metals, such as mercury.
- To have an advanced age
Although it is known that these risk factors influence the onset and development of the disease, the cause of myelodysplastic syndromes is not known in the majority of cases.
There are different types of treatments to treat myelodysplastic syndromes. The choice of a specific treatment depends on multiple factors among which is for example the type of damaged cell or the symptoms of the patient.
The treatments can be classified basically into two groups, the traditional or standard ones and those that are under evaluation. The traditional treatments are those that are used normally, but, if the results of the evaluation of another treatment are obtained and these are favorable, the treatment under evaluation becomes a standard treatment.
Currently, three types of standard treatments are used:
- Supportive medical care . This type of treatment includes a series of measures aimed at improving the problems caused by both the disease and other treatments received (such as radiotherapy) and include:
- Transfusion therapy . Blood transfusions are used to increase the levels of healthy red blood cells, white blood cells and platelets in patients. The transfusion of red blood cells is usually used when a blood test shows low levels of red blood cells and the patient has anemia. Platelet transfusion is performed when patients have hemorrhages or are going to undergo a procedure that is likely to bleed and when low levels of platelets appear in an analytic. Transfusion therapy has a problem and that patients who receive many blood transfusions can be damaged in some tissues and organs by the accumulation of iron, although this excess iron can be treated with a chelation therapy.
- Administration of substances stimulating erythropoiesis (SEE). ESS helps increase levels of mature blood cells and lessen anemic symptoms. Sometimes they are combined with a substance called granulocyte colony stimulating factor (FEC-G) to increase its effectiveness.
- Therapy with antibiotics . It is very common that patients with low levels of white blood cells suffer infections, which is why they are usually prescribed antibiotics.
- Therapy with medicines.
- Immunosuppressive therapy. The immunosuppressive therapy is used because it is sometimes the immune system of patients themselves who deteriorates and kill red blood cells. To alleviate this, a substance called antithymocyte globulin (GAT) is administered, which weakens the immune system. This measure helps to reduce the number of red blood cell transfusions needed.
- Azacitina and decitabine . These drugs kill cells that divide uncontrollably, and increases the effects of the genes responsible for making the cell mature. This treatment can significantly improve myelodysplastic syndromes by preventing or decreasing the chances of it degenerating into a leukemia.
- The chemotherapy is used in MDS patients in which an excessive number of blasts in bone marrow is observed, since they have quite likely to develop leukemia.
- Chemotherapy with stem cell transplant . In many cases, stem cell transplants are performed after finishing the chemotherapy to restore damaged cells with the treatment. Stem cells are obtained from the blood or bone marrow of a donor and stored frozen. When the patient completes the chemotherapy, the stem cells are thawed and administered to the patient by infusion.