OVERVIEW

What is Myelodysplastic Syndrome?

Human blood cells originate from hematopoietic stem cells in the bone marrow. These stem cells differentiate into progenitor cells, which then undergo a series of complex processes to develop into blood cell components such as red blood cells, platelets, and white blood cells.

Myelodysplastic syndrome occurs when hematopoietic stem cells in the bone marrow become abnormal and proliferate uncontrollably, leading to ineffective hematopoiesis. It is primarily characterized by a reduction in peripheral blood cells and carries a high risk of progressing to acute myeloid leukemia (commonly known as blood cancer or leukemia).

Is Myelodysplastic Syndrome Benign or Malignant?

Myelodysplastic syndrome results from the uncontrolled abnormal growth of hematopoietic stem cells in the bone marrow (also called "clonal proliferation"). Although it does not metastasize throughout the body like typical malignant tumors, it has the potential to transform into acute myeloid leukemia. Additionally, the cytopenia caused by this disease is extremely difficult to treat, making it a highly malignant condition.

How Common is Myelodysplastic Syndrome?

Myelodysplastic syndrome is relatively common among patients visiting hematology departments, though nationwide incidence statistics are currently unavailable in China.

The disease most frequently affects the elderly, but its exact incidence rate remains unclear. The risk of myelodysplastic syndrome increases with age. One study estimated the annual incidence rates as follows: <50 years: 0.5/100,000; 50-59 years: 5.3/100,000; 60-69 years: 15/100,000; 70-79 years: 49/100,000; and ≥80 years: 89/100,000.

Note: Annual incidence = New cases per year / Total population

SYMPTOMS

What are the initial symptoms of myelodysplastic syndrome?

Among all manifestations of myelodysplastic syndrome, most patients present with anemia as the earliest symptom, which is difficult to control.
It should be noted that anemia is not specific to myelodysplastic syndrome and can also occur in many other diseases.

Why does myelodysplastic syndrome cause cytopenia?

The bone marrow of patients with myelodysplastic syndrome is in a hyperproliferative state compared to that of healthy individuals. However, this proliferation is abnormal and pathological, unable to produce effective hematopoiesis like normal bone marrow proliferation.

What are the main factors threatening the lives of patients with myelodysplastic syndrome?

The primary factors are complications caused by ineffective hematopoiesis in the bone marrow. Approximately 50% of patients die from bleeding due to thrombocytopenia or severe infections caused by leukopenia that are difficult to control. About 30%–40% of patients die from leukemia after progression, while 10%–20% die from other complications unrelated to the disease itself, such as immunosuppression after chemotherapy or complications following hematopoietic stem cell transplantation.

What are the manifestations of myelodysplastic syndrome?

Myelodysplastic syndrome develops slowly, and patients typically experience related discomfort only weeks after onset. The symptoms are mainly caused by cytopenia, such as anemia due to reduced red blood cells, bleeding due to thrombocytopenia, and recurrent infections due to leukopenia.

CAUSES

What are the causes of myelodysplastic syndrome?

To date, the exact causes and mechanisms of myelodysplastic syndrome remain unclear. Current research has only confirmed that certain factors are closely associated with the disease, but whether they directly cause it remains uncertain. The main high-risk factors include: radiotherapy, alkylating agent chemotherapy, benzene, chloramphenicol, and ethylenimine.

At what age does myelodysplastic syndrome most commonly occur?

Myelodysplastic syndrome primarily affects the elderly and is less common in children and young adults.

Is there a gender difference in the occurrence of myelodysplastic syndrome?

The disease is more prevalent in males than females, with a male-to-female ratio of approximately 1.8:1.

Is myelodysplastic syndrome hereditary?

About 40%–60% of myelodysplastic syndrome patients exhibit chromosomal abnormalities, and 3%–40% have abnormal gene mutations. However, there is no definitive evidence to determine whether these abnormalities are congenital or acquired. What is certain is that this disease is not hereditary.

DIAGNOSIS

What tests should be done for myelodysplastic syndrome?

For patients suspected of having myelodysplastic syndrome, the following tests are essential: complete blood count, folate, vitamin B12, ferritin, erythropoietin, bone marrow aspiration for cytological smear, and bone marrow biopsy. With the advancement of modern medicine, genetic testing has also become mandatory. Medical institutions with the necessary resources should additionally perform bone marrow culture.

How is myelodysplastic syndrome diagnosed?

To confirm a diagnosis of myelodysplastic syndrome, all of the following prerequisites and at least one of the definitive criteria must be met:

• Prerequisites:
  • Persistent reduction in one, two, or all three blood cell lines (reduction criteria: hemoglobin <100 g/L, platelets <100×10^9/L, neutrophils <1.5×10^9/L);
  • Exclusion of other similar diseases.
• Definitive criteria:
  • Dysplasia in bone marrow, with ≥10% abnormal cells in at least one hematopoietic cell lineage;
  • Ring sideroblasts accounting for ≥15% of nucleated red blood cells;
  • Blast cells comprising 5%–19% of bone marrow smear cells;
  • Presence of common chromosomal abnormalities associated with myelodysplastic syndrome.
    Despite rapid medical advancements, this disease remains fundamentally a diagnosis of exclusion. It can only be confirmed after ruling out similar conditions and correlating with clinical manifestations.

Which diseases resemble myelodysplastic syndrome?

• Vitamin B₁₂ and folate deficiency;
• Patients undergoing chemotherapy, cytokine therapy, or exposure to toxic chemicals and biologics;
• Anemia of chronic disease, such as infections or tumors;
• Chronic liver disease, HIV/AIDS;
• Heavy metal poisoning;
• Cytopenia caused by autoimmune diseases, hypothyroidism, and other thyroid disorders;
• Other diseases affecting hematopoietic stem cells, such as aplastic anemia, paroxysmal nocturnal hemoglobinuria, myelofibrosis, congenital neutropenia, etc.
  Diagnosis of myelodysplastic syndrome requires exclusion of the above-mentioned conditions.

How is the severity of myelodysplastic syndrome classified?

The severity of myelodysplastic syndrome is determined by multiple indicators. After diagnosis, the disease is categorized into varying risk levels based on the percentage of blast cells in the bone marrow, the degree of cytopenia, and bone marrow cytogenetic features.

Assessing disease severity is complex and generally requires evaluation by a specialized hematologist.

TREATMENT

What are the current treatment options for myelodysplastic syndrome?

Since the cause and pathogenesis of this disease remain unclear, there is no unified treatment plan domestically or internationally. The following treatment options are available:

• Hematopoietic stem cell transplantation: Currently the only curative treatment for this disease.
• Supportive therapy (symptomatic treatment): Such as blood transfusion for cytopenia, infection control, iron chelation therapy, and hematopoietic growth factors.
• Biological response modifier therapy: Thalidomide or lenalidomide immunotherapy may improve hematopoiesis in some patients. Immunosuppressants can be used for certain low-risk MDS cases.
• Gene expression-modifying therapy (hypomethylating therapy): Decitabine is currently an option.
• Chemotherapy: Especially for patients progressing to acute myeloid leukemia, treatment follows leukemia protocols.

How does treatment differ between pediatric and adult patients with myelodysplastic syndrome?

For children diagnosed with pediatric myelodysplastic syndrome, hematopoietic stem cell transplantation is the preferred treatment, offering a high cure rate. Adult patients receive different treatments based on risk level, physical condition, and treatment compliance.

What treatment goals should adult patients with myelodysplastic syndrome establish?

Since hematopoietic stem cell transplantation success rates are lower in adults than in children, treatment strategies and goals vary. For very low-risk, low-risk, and intermediate-risk patients, the goal is to improve hematopoiesis and quality of life, not necessarily cure.

For high-risk patients, the goal is to delay disease progression, prolong survival, and achieve cure if possible.

Which patients with myelodysplastic syndrome are eligible for hematopoietic stem cell transplantation?

• Pediatric myelodysplastic syndrome patients without contraindications (first-line treatment).
• Patients <65 years old in high-risk or very high-risk groups.
• Patients <65 years old with severe cytopenia unresponsive to non-transplant therapies (low/intermediate-risk).

What are the possible outcomes of myelodysplastic syndrome?

• Cure: Mainly seen in select patients undergoing hematopoietic stem cell transplantation.
• Long-term disease stability with supportive care alone.
• Initial stability followed by sudden progression to acute myeloid leukemia.
• Progressive transformation to acute myeloid leukemia from disease onset.

What is the overall survival time for myelodysplastic syndrome?

• Very low-risk: ~141 months.
• Low-risk: ~66 months.
• Intermediate-risk: ~36 months.
• High-risk: ~26 months.
• Very high-risk: ~9 months.

What factors indicate poor prognosis in myelodysplastic syndrome?

• High blast percentage in bone marrow.
• Chromosomal abnormalities (especially chromosome 7 abnormalities, though -Y, 5q-, and 20q- indicate better prognosis).
• Low peripheral blood cell counts.
• Age >65 years.

DIET & LIFESTYLE

What should patients with myelodysplastic syndrome pay attention to?

• Maintain an optimistic attitude, especially for patients diagnosed as low-to-intermediate risk. Understand that the treatment goal is not cure but improving quality of life. With proper care, infection prevention, and adequate supportive treatment, long-term survival with the disease is possible;
• Although hematopoietic stem cell transplantation is the only curative method, current techniques still require further refinement. Therefore, careful consideration is needed before opting for transplantation, particularly for low-to-intermediate risk patients;
• Children diagnosed with myelodysplastic syndrome should receive hematopoietic stem cell transplantation as soon as possible once conditions permit.

PREVENTION

None.