What is Myelodysplastic Syndrome (MDS)?
MDS is a syndrome of abnormal stem cells in the spinal cord. These stem cells divide into immature cells, called blast cells. Once blast cells are mature, they will present with unique characteristics which can be categorized into three types of blood cells, including red blood cells, white blood cells, and platelets. MDS patients have an abnormality in stem cell function that is unable to produce enough normal blood cells and platelets, which results in illness.
Up to 30% of MDS patients develop acute leukemia, which is more life-threatening.
About 87,000 new patients worldwide are diagnosed with MDS each year. In the United States, about 10,000-20,000 new patients are found annually; however, official statistical data of these patients has not been available in Thailand.
At the time of diagnosis, MDS patients do not present their symptoms. As the cause of this disease is lower production of blood cells than normal, thus signs and symptoms depended upon the deficiency level of blood cells and platelets.
- Low red blood cells Patients present with anemia, easily tired, fatigue, palpitation, headache, irritability, and paler skin than normal.
- Low white blood cells Patients are more likely to become infected than normal, have a fever, or be chronically ill.
- Low platelets Patients present with gum and skin bleeding, bruising skin, bruises. Bleeding in the cornea may cause vision disorder.
Causes of MDS
The causes of MDS are not clearly known. A contaminated environment with toxins, chemicals, and radiation may contribute to MDS. However, the exact cause is radiation exposure and chemotherapy used for cancer treatment, which can be found in 10-20% of patients.
Risk factors of MDS
Conditions that contribute to more MDS occurrence are:
- Age: commonly found in people aged over 60.
- Gender: more commonly found in men than women.
- Race: more commonly found in caucasians than others.
- Occupation: Workers with regular chemical exposure, e.g. farmers using pesticides, chemists, workers in textile factories working in environments in which insecticides are used, workers in industrial plants, workers in gas stations.
MDS diagnosis guideline
MDS is an abnormality syndrome. Symptoms may be varied in subgroups of patients. MDS is classified into 8 groups according to World Health Organization classification, which is currently used as a global standard, by using the following criteria including: morphology of blood smear, changes in bone marrow, and cytogenic study. The MDS classification into different subgroups is a good indicator to point out the possibility of development of the disease into leukemia in the future.
Laboratory tests that are necessary to classify MDS type include:
- Complete blood count and morphology of blood cells: complete blood count, differential count, platelet count, and peripheral blood smear
- Kidney function test serum blood urea nitrogen/creatinine, electrolyte
- Liver function test AST, ALT, alkaline phosphatase, total/direct bilirubin
- Blood iron count serum ferritin, serum iron, TIBC
- Bone marrow investigations bone marrow aspiration/biopsy, bone marrow cytogenetic study, iron stain
- Hepatitis B and C test HBs Ag, AntiHBsAb, AntiHCV
MDS patients are categorized by risk factors. Each group has a different survival period and leukemia risk ratio. There are 2 systems used to classify patients including:
International Prognostic Scoring System (IPSS) Patients will be assessed by 3 parameters, e.g. marrow blast count, karyotype, and cytopenia. Rating of each parameter will depend on the patient’s condition. Then risk level will be grouped by total score, e.g. low risk (low and intermediate-1), and high risk (intermediate-2 and high)
WHO Prognostic Scoring System (WPSS) Patients will be assessed by WHO-based morphology, IPSS cytogenetic study, and blood transfusion condition to correct anemia. WPSS classified patients into 4 groups, i.e. very low, low intermediate, high, very high
MDS treatment guideline
MDS treatment guideline consists of supportive treatment (e.g. blood transfusion in anemic patients), and specific treatments as per risks of leukemia development, i.e. low risk or high risk.
MDS treatment guideline for low risk patients
The main objective is to treat cytopenia. Most treatments are supportive including blood transfusion in anemic patients. Other treatments include:
- Cytokine support: erythropoietin administration or erythropoietin combined with G-CSF
- Immunosuppressive agents
- Immunomodulating agents
- Hypomethylating agents
- Bone marrow transplantation
MDS treatment guideline for high risk patients
It mainly depends on the patient’s and doctor’s decision. Clinical factors influencing the decision include: patient’s age, daily activity performance status, comorbidities, patient’s mental and social status, patient’s impression, and treatment readiness. The guideline includes:
- Hypomethylating agents
- Bone marrow transplant