The term Myelodysplastic syndromes (MDS) encompass a type of bone marrow cancers in which 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 verify that everything is going well because, at the beginning, the symptoms are not perceptible. 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 of breathing and the feeling of continuous tiredness.
The life expectancy of people suffering from MDS is very heterogeneous as it depends on the type of specific syndrome as well as other factors such as age or substances to which they have been exposed in their life (chemical substances, heavy metals...) .
Characteristics of myelodysplastic syndromes
In order to understand what the myelodysplastic syndromes are before we must know what the normal functioning of the bone marrow And blood cells.
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 mother cell or a myeloid stem cell. The Lymphocytes Mature into white blood cells while 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 infection and disease.
Myelodysplastic syndrome is characterized because 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 stage of maturity, forming cells called blasts.
The blasts do not work as they should and have a very short life, dying shortly after coming to the blood or in the same bone marrow, leaving little space for healthy cells that if they could mature.
When the level of healthy blood cells drops drastically the person can suffer problems such as infections, anemia or frequent bleeding.
Signs and symptoms
Usually the symptoms of these syndromes are not noticeable until the person already has a time with the disease. Although each syndrome has different characteristics, they all share the following symptoms:
- Respiration problems.
- Weakness and tiredness.
- Paleness of skin (more than usual).
- Bruising and bleeding easily.
- Petechiae (spots on the skin that form when bleeding occurs near the skin, but there is no wound through which blood can escape).
Types of myelodysplastic syndromes
Myelodysplastic syndromes differ in the type of blood cell involved, so it is necessary to perform accurate 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 deletion5q isolated.
Refractory cytopenia with unilinear dysplasia (RCUD)
Between 5 and 10% of patients with a myelodysplastic syndrome have 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. In addition, not all blood cells of this type are affected, there are only problems in about 10% of the cells (dysplasia).
Within this group the following syndromes are included:
- Refractory anemia (RA). RA is the most common type of RCUD. In this syndrome the affected blood cells are red blood cells, which have very low blood levels. The levels of the remaining blood cells and blasts are normal.
- Refractory neutropenia (RN)
- Refractory thrombocytopenia (RT)
Sometimes a RUDD can degenerate into an acute myeloid leukemia, but it is not very common. Patients with RUDD often live for a long time and have a good quality of life.
Refractory anemia with ringed sideroblasts (RARS)
Between 10% and 15% of patients suffering from myelodysplastic syndrome have refractory anemia with ringed sideroblasts (RARS).
This syndrome is very similar to refractory anemia, also affected only the red blood cells. 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 that these cells are called ring sideroblasts.
As with RUDCs, rare RARS can degenerate into leukemia, and it is normal for patients to live for an extended period of time.
Refractory cytopenia with multilineage dysplasia (RCMD)
This is the most common type of myelodysplastic syndrome, about 40% of patients with SD have refractory cytopenia with multilinear dysplasia (RCMD).
RCMDs are characterized because at least two types of blood cells are affected, while the others are intact, and the number of blasts in both blood and 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 with this syndrome have a short life expectancy, it is estimated that about half of patients die within two years of the diagnosis.
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 in 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. Blastocytes do not contain Auer rods, 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 from 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 conform up to 20% of the blood cells of the marrow.
They also differ in that there is an excess of blastocytes also in the blood, where between 5 and 19% of the white blood cells have not matured and have remained blastocytes. These blasts may contain Auer rods.
The probability that a patient with RAEB-2 will develop acute myeloid leukemia is very high, about 50%. Therefore, patients with this syndrome have a poor prognosis.
Myelodysplastic syndrome associated with (5q) isolated
The main characteristic of this syndrome is that the chromosomes in the blood stem cells lack chromosome 5 and that leads to them to develop in an abnormal way.
Red blood cell levels are a bit low and patients may have anemia, while white blood cell levels are normal and platelet levels can be even increased.
Patients with this syndrome usually do not develop leukemia And have a fairly favorable prognosis with a long life expectancy.
Unclassified myelodysplastic syndrome (MDS-U)
This syndrome is the least common of all myelodysplastic syndromes. Any MDS-compliant syndrome with abnormalities in blood cells is diagnosed as MDS-U but does not meet the criteria for any particular MDS.
This group includes patients with very different characteristics, making it difficult to establish a general prognosis.
Risk factor's
There are factors that may increase the likelihood of myelodysplastic disorder, such as:
- Have had chemotherapy or radiation therapy, 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.
- Having an old age.
Although these risk factors are known to influence the onset and development of the disease, the cause of myelodysplastic syndromes is not known in most cases.
Treatment
There are different types of treatments to treat myelodysplastic syndromes. The choice of a particular treatment depends on multiple factors including, for example, the type of cell damaged or the patient's symptoms.
Treatments can be classified basically into two groups, traditional or standard and those in evaluation. Traditional treatments are those that are normally used, but if the results of the evaluation of another treatment are obtained and these are favorable, the treatment in evaluation becomes a standard treatment.
Standard Treatments
Three types of standard treatments are currently used:
- Supportive care . This type of treatment includes a series of measures to improve the problems caused by the disease as well as other treatments received (such as radiotherapy) and include:
- Transfusion therapy . Blood transfusions are used to raise the levels of red blood cells, white blood cells and Platelets Healthy in patients. Red blood cell transfusion is usually used when a blood test shows low red blood cells and the patient has anemia. Platelet transfusion is performed when patients have bleeding or are going to undergo a procedure that will probably make them bleed and when in an analytic low platelet levels appear. Transfusion therapy has a problem and is that patients who receive many blood transfusions can suffer damage in some tissues and organs by the accumulation of iron, although this excess iron can be treated with a chelation therapy.
- Administration of erythropoiesis stimulating substances (SEE). SEE helps to increase mature blood cell levels and lessen anemic symptoms. They are sometimes combined with a substance called granulocyte colony stimulating factor (G-CSF) to increase its effectiveness.
- Therapy with antibiotics . It is very common for patients with low white blood cells to get infections, so antibiotics are often prescribed.
- Therapy with medicines .
- Immunosuppressive Therapy . The Immunosuppressive therapy Is used because it is sometimes the patients' own immune system that deteriorates and ends with red blood cells. To alleviate this, a substance called antithymocyte globulin (GAT), which weakens the immune system, is administered. This measure helps decrease the number of red blood cell transfusions needed.
- Azacillin 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 dramatically improve myelodysplastic syndromes by preventing or decreasing the chance of this degeneration in leukemia.
- The chemotherapy Is used in patients with MDS in whom an excessive number of blasts are observed in their bone marrow, since they are quite likely to develop leukemia.
- Chemotherapy with stem cell transplantation . In many cases, stem cell transplants are performed after chemotherapy is completed to restore damaged cells with treatment. Stem cells are obtained from a donor's blood or bone marrow and stored frozen. When the patient completes the chemotherapy the stem cells are thawed and administered to the patient by infusion.
References
American Cancer Society. (July 2, 2015). Types of myelodysplastic syndromes . Retrieved from the American Cancer Society.
Josep Carreras Foundation. (S.f.). Myelodysplastic syndromes . Retrieved on June 15, 2016, from Josep Carreras Foundation.
National Cancer Institute. (August 12, 2015). Myelodysplastic Syndromes Treatment (PDQ®) -Patient Version . Obtained from National Cancer Institute.
National Library of Medicine. (S.f.). Myelodysplastic Syndromes . Retrieved on June 15, 2016, from MedlinePlus.