Myeloproliferative Neoplasms

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What are Myeloproliferative Neoplasms (MPNs)

Myeloproliferative Neoplasms (MPNs) are a group of rare conditions that affect the blood. In MPNs, something goes wrong with the normal production of blood cells, the bone marrow may produce too many of one or more particular types of blood cell or in some cases too few blood cells.

The bone marrow is the spongy material inside the bones where new blood cells are produced. The normal process of blood cell production starts with a stem cell, which is an immature cell that can develop into all types of blood cell. When the stem cell divides, it can either produce more stem cells or produce immature blast cells with the potential to further develop and mature.

The immature blast cells can mature and develop in the bone marrow to become the three types of blood cells: red blood cells, white blood cells, or platelets. All blood cells have an important function.

  • Red blood cells (also called erythrocytes) – carry oxygen around the body to organs and tissues.
  • White blood cells (also called leukocytes) – protection against illness & disease by fighting infections.
  • Platelets (also called thrombocytes) – help blood clot to prevent bruising and bleeding.

Myeloproliferative Neoplasms (MPNs) symptoms

Symptoms of myeloproliferative neoplasms are likely to vary and many people with MPNs do not experience any signs. For those that do suffer from symptoms*, the most common signs of MPNs can include:

  • Bruising and or unusual bleeding
  • Night sweats
  • Frequent infections
  • Fatigue
  • Unexplained weight loss

It’s important to remember symptoms of MPNs can vary and your doctor will be able to offer advice on any questions you may have.

Myeloproliferative Neoplasms facts

  • Approximately, 4,180 are diagnosed with MPN in the UK each year.
  • Polycythaemia vera (PV) is rarely diagnosed before the age of 40 years and more common in men than women.
  • Essential thrombocythaemia (ET) is most commonly diagnosed in people over 60 years.
  • Myelofibrosis can affect anyone but it is most common in people over 50 years.
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The World Health Organisation (WHO) classifies MPNs as a type of blood cancer because the bone marrow produces blood cells in an uncontrolled way.

The three common types of MPNs are separated into different disorders as each of them affect levels of blood cell in a different way. The three most frequently diagnosed types of MPN are:

  1. Polycythaemia vera (PV)
  2. Essential thrombocythaemia (ET)
  3. Myelofibrosis (MF)

Polycythaemia vera (PV)

PV is type of MPN and considered a rare disease. PV is caused by the overproduction of red blood cells in the bone marrow but sometimes too many platelets and white blood cells, which then build up in the blood. Blood may often be thicker than normal.

In 30% of people with PV, the excess number of red blood cells may cause blood clots to form more easily making the person more susceptible to a stroke or heart attack.

Essential thrombocythaemia (ET)

ET is a type of MPN, a rare chronic condition characterised by too many platelets in the blood. Although platelets are primarily affected, levels of white blood cells may also be elevated.

In people diagnosed with ET, the blood becomes thicker than normal, and the excess number of platelets may cause blood clots to form more easily. Clots may block blood flow through veins and arteries, potentially leading to heart attacks or strokes. ET is also associated with an increased risk of bleeding complications.

Myelofibrosis (MF)

MF is a type of MPN, characterised by excessive scar tissue in the bone marrow. In MF, abnormal blood stem cells in the bone marrow produce mature cells too quickly which then occupy the bone marrow, leading to the formation of scar tissue (fibrosis). The formation of the scar tissue in the bone marrow prevents the production of healthy normal blood cells. MF can occur on its own or following diagnosis with another type of MPNs, polycythaemia vera (PV) or essential thrombocythemia (ET).

There are two main types of MF:
  • Primary myelofibrosis: This type of MF occurs spontaneously.
  • Secondary myelofibrosis: This type occurs following a previous diagnosis with another MPN such as ET or PV.
  • Treatment for myeloproliferative neoplasms

    Treatment will be dependent on the type of MPNs and is usually aimed at controlling the number of blood cells.

    It’s important to remember that everybody reacts differently to various forms of treatment, and your doctor will be able to offer further advice and information about other treatments available for MPNs.

    Treatments for MPNs* can include:

    • Venesection, which is a procedure to reduce the number of blood cells
    • Taking specific medication to control the blood count
    • A bone marrow or stem cell transplant
    • In some cases chemotherapy may be used

    We firmly believe that research has the power to make a difference and truly change lives. Our research team at Leukaemia UK are constantly researching kinder and more effective treatments for different types of leukaemia, which could also help with MPNs.

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