Myelodysplastic syndrome (MDS)What is Myelodysplastic syndrome
Myelodysplastic syndrome (MDS) describes a group of bone marrow disorders that are characterised by a defect in stem cells. The bone marrow is the tissue located in the centre of long bones in the body and is responsible for producing most of the cells in the body. Stem cells are the precursor cells that divide and grow to produce each of the particular cell lineages. Haemopoetic stem cells produce cells in the blood of three classes- white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes). In Myelodysplastic syndrome (MDS) the stem cells become mutant and are no longer able to divide effectively into each of the blood cells. The normal bone marrow gradually becomes replaced with the mutant cells and there is a fall in each of the different cells within the bloodstream. Patients with this disorder therefore typically have anaemia, neutropenia and thrombocytopenia (low platelets). The latter two can predispose to infection and bleeding. The abnormal cells in the bone marrow can also transform and cause syndromes also pose a risk of transformation to Acute Myeloid Leukaemia (AML).
Who gets Myelodysplastic syndrome?
The true incidence of Myelodysplastic syndrome (MDS) is difficult to estimate as it has only recently been regarded as a distinct class of disorders and controversies exist regarding its classification. However, MDS is now considered as common as Acute Myeloid Leukaemia (AML) and more cases are beginning to be recognised. MDS is most common in elderly patients as they are more prone to bone marrow damge but it can occur in any ae group. The overall incidence is thought to be around 0.5-4 cases per one million people per year.
Predisposing Factors
The risk of MDS increases with age where patients usually older than 50 years get the primary form (no known exposure) of the disorder. The second type of MDS is acquired following drug treatments or radiotherapy that damage the bone marrow. This type accounts for most cases under fifty years of age and arises 2-8 years following the damaging treatment. Certain genetic defects (such as Down syndrome), cigarette smoking, benzene exposure and DNA repair disorders can also increase your risk of this condition. Males are affected slightly more common than females in all age groups.
Progression
The mechanism of development of MDS is not known. The course of the disease is variable, but serious complications of bone marrow failure, and transformation into acute myeloblastic leukaemia commonly occur. Patients may also get infections (due to reduced neutrophils that normally fight diseases) and bleeding problems (due to reduced platelets). The therapy-related form of the disease is normally much worse and rapidly progresses to cause a fall in red blood cells, neutrophils and platelets within the bloodstream.
Probable Outcomes
The median survivial in primary (non-therapy related) MDS varies from 9 to 29 months, although some individuals in good prognostic groups live for 5 years or more. Overall, progression to AML occurs in around 30%. Other causes of death include bleeding and infection due to the reduction in platelets and neutrophils respectively. Patients with therapy-related MDS have a much worse outlook and most only survive for 4-8 months following the diagnosis.
How Will Myelodysplastic syndrome Affect Me?
The signs and symptoms of this disorder are quite non-specific and a significant proportion of patients may have no symptoms at all. These patients are sometimes diagnosed by routine blood tests for other disorders, that happen to identify abnormal or reduced numbers of certain cells in the peripheral blood. If symptoms do occur, the most common are fatigue, weakness, reduced exercise tolerance and dizziness which is caused by the underlying anaemia (reduction in oxygen carrying red blood ceels in the blood). You may also notice symptoms of infection such as fever, cough or discomfort urinating as your body is more prone to bacterial and other infections due reduced neutrophils. Reduced platelets can cause easy bruising and bleeding from the gums or nose. If you have any of the above symptoms you should talk to your doctor. They will ask you a more detailed history about your symptoms and any possible predisposing factors to the disorder (such as certain chemotherapy drugs).
Clinical Examination
Your doctor will carefully examine you and may identify several particular signs that suggest the diagnosis of MDS. Often you will appear pale due to anaemia of the doctor may detect a rapid heart rate or signs of heart failure. Signs of infection include fever, rigors, chills, sweating and increased heart rate. Your doctor will also carefully examine your skin, gums and nose for signs of bleeding. They may also take a urine or stool sample to determine the presence of blood. In addition, they will gently feel your stomach and may identify a big spleen which is associated with a particula, advanced type of the disease.
How is Myelodysplastic syndrome Diagnosed?
The most common test performed is a full blood count that shows low haemoglobin (oxygen carrying protein), low red cell count, low white cell count, high monocytes, and low platelets. These abnormalities may occur alone or in combination but later stages of disease are characterised by deficiencies in all cell types. The cells also have abnormal shapes and appearances that help the doctor make the diagnosis. In addition, a bone marrow biopsy (sample of bone marrow) is often taken to confirm the diagnosis as this can visualise the actual abnormal precursor cells.
How is Myelodysplastic syndrome treated?
Treatment of MDS largely aims to control the symptoms of the underlying cellular deficiencies and reduce progression of disease without causing severe side effects. Patients with mild disease and less than 5% blasts cells (abnormal precursors) in the bone marrow, will usually be managed conservatively with red cell and platelet transfusions and antibiotics for infections, as they are needed. Patients with more severe disease and more than 5% blast cells in the bone marrow, will require more aggressive treatment. A number of options are available, including: supportive care only, low-dose chemotherapy, intensive chemotherapy, and bone marrow transplantation. The choice of treatment will depend on your age, risk of disease and current performance status. Note that many of the treatments for MDS are fairly new and still under investigation. The mainstay of treatment for all patients is therefore to focus on prompt treatment of infection, bleeding complications and anaemia. Information on other types of leukaemia:
- Chronic Myeloid Leukaemia
- Promyelocytic leukaemia
- Multiple myeloma
- Chronic cymphocytic leukaemia
- Acute lymphoblastic leukaemia
- Acute myeloid leukaemia
Myelodysplastic syndrome References
- Besa E, Woermann U. Myelodysplastic Syndrome, eMedicine, Web MD, 2006. Available [online] at URL: http://www.emedicine.com/med/topic2695.htm
- Cotran RS, Kumar V, Collins T. Robbins Pathological Basis of Disease, Sixth Ed. WB Saunders Company 1999. p 678.
- Doll D, Landaw S. Clinical manifestations and diagnosis of the myelodysplastic syndromes, UpToDate, 2006.
- Estey E, Schrier S. Treatment and prognosis of the myelodysplastic syndromes, UpToDate, 2006.
- Kumar P, Clark M. Clinical Medicine. Fifth Ed. WB Saunders, 2002. p 390
- Longmore, Wilkinson, Rajagopalan. Oxford Handbook of Clinical Medicine. 6th Edition. Oxford University Press. 2004.
- Murtagh J. General Practice, 3rd Ed. McGraw-Hill, Australia, 2003.
Treatments Used in This Disease:
Drugs/Products Used in the Treatment of This Disease:
Vidaza(Azacitidine)
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