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Myelodysplastic Syndromes (MDS) – Adults

Myelodysplastic Syndromes Overview

Myelodysplastic syndromes (MDS) represent a group of different bone marrow disorders characterized by the bone marrow’s inability to produce adequate healthy blood cells. These syndromes arise due to mutations in the hematopoietic stem cells, which lead to dysfunctional blood cell production, manifesting in anemia, infections and bleeding, as immature or abnormal cells proliferate. While the exact trigger for these mutations is often unclear, factors like genetic predispositions, environmental exposures and previous chemotherapy or radiation treatments are linked to the development of MDS. Although considered rare, MDS are primarily diagnosed in older adults, with cases increasing with age. The incidence of MDS varies globally but is estimated to affect approximately 4 out of 100,000 people annually. However, this rate is likely higher in older populations, underlining the importance of understanding these complex conditions, which can progress to acute myeloid leukemia in some patients.

Myelodysplastic Syndromes (MDS) - Adults

MDS Types

Myelodysplastic syndromes are classified into several types, depending on the nature and severity of the blood cell dysplasias.

MDS with Single Lineage Dysplasia (MDS-SLD)

In MDS-SLD, one cell lineage (red cells, white cells, or platelets) is dysplastic. It is characterized by unilineage dysplasia, meaning only one type of blood cell is affected, and these patients typically have cytopenia (a reduction in the number of mature blood cells).

MDS with Multilineage Dysplasia (MDS-MLD)

MDS-MLD involves two or more myeloid cell lines. This subtype often presents more complex symptoms since multiple types of blood cells are typically low in number and not functioning properly.

MDS with Ring Sideroblasts (MDS-RS)

When ring sideroblasts (abnormal red blood cells with rings of iron-loaded mitochondria) are present, the condition is classified as MDS-RS. There are two subtypes:

  • MDS-RS with Single Lineage Dysplasia (MDS-RS-SLD): Characterized by ring sideroblasts comprising 15% or more of the marrow erythroid cells and single lineage dysplasia.
  • MDS-RS with Multilineage Dysplasia (MDS-RS-MLD): This type shows dysplasia in two or more myeloid cell lines with the presence of ring sideroblasts.

MDS with Excess Blasts (MDS-EB)

MDS-EB refers to MDS subtypes with an increased number of blasts (immature cells) in the bone marrow or blood. It is further categorized into:

  • MDS-EB1: With blasts comprising 5-9% of the blood or 5-10% in the bone marrow.
  • MDS-EB2: Where blasts make up 10-19% of the blood or 10-20% in the bone marrow.

MDS with Isolated del(5q) Chromosome Abnormality

This subtype features a specific deletion on chromosome 5. Patients usually present with macrocytic anemia while having normal or increased platelet counts.

MDS, Unclassifiable (MDS-U)

When the criteria do not meet the above categories, the syndrome is classified as MDS-U, a less common and more ambiguous category.

In all these subtypes, there is a risk, to varying degrees, of progression to acute myeloid leukemia (AML), a potentially severe complication where the bone marrow produces a high number of immature white cells.

MDS Causes and Risk Factors

While the exact causes of MDS are not fully understood, a combination of genetic and environmental factors is believed to contribute to its development.
  • Age: One of the most significant risk factors for MDS is age; the majority of MDS cases occur in individuals over the age of 60. This suggests that the cumulative effect of cellular damage over time may play a crucial role in the development of the disease. Environmental factors, such as tobacco smoke, pesticides and industrial chemicals like benzene, have also been implicated in the onset of MDS. Long-term exposure to these substances can lead to DNA damage within the hematopoietic cells of the bone marrow, potentially triggering MDS.
  • Genetic: Genetic factors also influence the risk of developing MDS. Certain inherited genetic syndromes, such as Fanconi anemia or Shwachman-Diamond syndrome, are associated with a higher risk of MDS. Moreover, previous chemotherapy or radiation therapy for other cancers is a known risk factor. These treatments can cause mutations in the bone marrow cells that may lead to MDS, a condition sometimes referred to as "therapy-related MDS" (t-MDS).
  • genetic predisposition: A small percentage of MDS cases arise from a genetic predisposition, although these are quite rare. In these instances, other family members may have a history of MDS or related blood disorders, suggesting a heritable genetic abnormality that increases susceptibility to the disease.
  • Lifestyle: Lifestyle factors such as smoking and alcohol abuse may increase the risk, although their exact roles are less clearly defined. Overall, while the causes of MDS can be multifactorial and complex, understanding the risk factors is key for both prevention strategies and early detection efforts.

MDS symptoms

Myelodysplastic Syndromes (MDS) present with a range of symptoms stemming from inadequate or dysfunctional blood cell production:

  • MDS Anemia: A common symptom caused by reduced red blood cell counts, anemia in MDS often leads to persistent fatigue, weakness, shortness of breath, and pallor. As red blood cells carry oxygen throughout the body, their deficiency can significantly impact overall energy levels and organ function.
  • MDS Leukopenia / MDS Neutropenia: Leukopenia refers to a decrease in white blood cells, which are crucial for fighting infections. Neutropenia, a subset of leukopenia, is specifically a reduction in neutrophils and poses a high risk for infections that can be recurrent or severe due to the immune system’s compromised state.
  • MDS Thrombocytopenia: This condition involves a low platelet count, leading to increased bruising, abnormal bleeding, such as nosebleeds or gum bleeding, and longer bleeding times after injury. Platelets play a critical role in clotting, so their deficiency can result in excessive bleeding, even with minor trauma.

These symptoms can profoundly affect quality of life and daily functioning, and their severity can range from mild to life-threatening. The presence of any combination of these symptoms warrants medical evaluation to rule out MDS or other blood-related disorders.


MDS Diagnosis

Diagnosis of MDS requires a thorough clinical evaluation and several tests. A complete blood count (CBC) is typically the first step when a hematological abnormality is suspected. Peripheral blood smear may also be examined for dysplastic changes in blood cells. If these tests indicate potential MDS, a bone marrow biopsy and aspiration become crucial. These procedures provide samples for microscopic examination and enable the identification of dysplasia in the marrow, the assessment of cellularity, and the quantification of blasts.

Cytogenetic analysis can reveal chromosomal abnormalities, like del(5q), and is integral to the classification and prognostication of MDS. Additionally, molecular genetic testing can detect gene mutations that may influence the choice of treatment and prognosis. Flow cytometry is another tool used to examine the expression of surface markers on cells, helping pathologists distinguish between MDS and other hematological disorders.

MDS Treatment

Treatment for MDS aims to manage symptoms, improve quality of life, and reduce the risk of progression to acute myeloid leukemia. The therapeutic approach is tailored to each patient based on the specific MDS subtype, overall health, age and treatment goals.

For lower-risk MDS, treatments may include:

  • Supportive care, such as red blood cell or platelet transfusions, to manage anemia and thrombocytopenia.
  • Erythropoiesis-stimulating agents (ESAs) to stimulate red blood cell production.
  • Iron chelation therapy to treat iron overload from frequent blood transfusions.
  • Immunosuppressive therapy for certain patients who may benefit from it.

For higher-risk MDS, treatment options are more aggressive and may include:

  • Hypomethylating agents, like azacitidine or decitabine, can lower the risk of transformation to AML and improve survival.
  • Chemotherapy may be used prior to a bone marrow transplant or as a standalone treatment.
  • Allogeneic bone marrow transplantation, the only potentially curative treatment, is usually considered for eligible patients, typically those who are younger and have a suitable donor.

Clinical trials are also a significant avenue for treatment, offering patients access to cutting-edge therapies that are being evaluated for effectiveness and safety.

MDS Prevention

Prevention strategies for MDS are not well-defined due to the diverse and often unclear causes of the syndrome. However, reducing exposure to known risk factors, such as tobacco smoke and industrial chemicals like benzene, may decrease the risk. Regular health checkups and prompt attention to hematological abnormalities can lead to early diagnosis and potentially more effective management.

Living with MDS

Living with MDS involves managing the physical and emotional challenges of the disease. This includes coping with the side effects of treatments, addressing nutritional needs, and managing fatigue. Psychological support is essential, as the diagnosis and ongoing management of MDS can be stressful and emotionally taxing. Support groups, counseling and education about the disease can empower patients and caregivers.

It is also critical for patients to maintain regular follow-ups with their healthcare team to monitor their condition and adjust treatment as needed. Palliative care services can be beneficial, focusing on providing relief from symptoms and improving the quality of life for patients and their families.

In conclusion, navigating the complexities of myelodysplastic syndromes (MDS) requires a thorough understanding of the disease, its symptoms, and the latest treatments. The Hemato-Oncology Department at Sheba Medical Center is at the forefront of this field, specializing in a wide range of hematological illnesses, including MDS, and offering state-of-the-art, tailored care – recognizing that each patient’s journey with MDS is unique.

With a commitment to comprehensive treatment and compassionate care, Sheba’s multidisciplinary team is dedicated to managing MDS and providing support systems for patients and their families. The center’s focus on innovation and research means patients have access to advanced therapies that aim not just to manage symptoms, but also to address the underlying causes of the disease.

For those seeking expert care, reach out to Sheba to discuss the variety of treatment options available.


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