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Myeloproliferative neoplasms

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on November 9, 2022.

Once referred to as myeloproliferative disorder, myeloproliferative neoplasms (MPNs) are a group of diseases in which the bone marrow makes too many red blood cells, platelets or white blood cells. MPN is a rare type of blood cancer.

According to the Leukemia & Lymphoma Society, around 20,000 people in the United States are diagnosed with a myeloproliferative neoplasm each year, and about 295,000 people are living with the disease.

The main types of myeloproliferative neoplasms are:

  • Chronic myelogenous leukemia (CML)
  • Polycythemia vera
  • Primary myelofibrosis
  • Essential thrombocythemia
  • Chronic neutrophilic leukemia
  • Chronic eosinophilic leukemia
  • Myeloproliferative neoplasms, unclassifiable (MPN-U)

These diseases become more challenging as the number of cells build up in the bloodstream and/or bone marrow and in some cases may be a precursor to leukemia.

This overview will cover the basic facts about MPNs, including:

Types of myeloproliferative neoplasms

MPNs are classified into subtypes based on:

  • Blood cell and platelet counts
  • Percentage of myeloid blasts in the bone marrow
  • Risk the disease will turn into leukemia

There are several types of MPNs:

Chronic myelogenous leukemia: Chronic myelogenous leukemia (CML) is a slowly progressing disease that occurs when the bone marrow makes too many white blood cells—and does not always cause symptoms. Most people with CML have a genetic mutation called the Philadelphia chromosome.

Polycythemia vera: Polycythemia vera occurs when too many red blood cells are produced in the bone marrow. Symptoms may include headaches and or fullness below the ribs on the left side.

Primary myelofibrosis (chronic idiopathic myelofibrosis): Primary myelofibrosis is characterized by abnormal blood cells and fibers in bone marrow. Symptoms may include pain below the ribs on the left side and extreme fatigue.

Essential thrombocythemia: Essential thrombocythemia may occur when too many platelets are made in bone marrow. With this type of condition, symptoms aren’t always present. Essential thrombocythemia may be caused by a genetic change to the JAK2 gene or CALR gene.

Chronic neutrophilic leukemia: In chronic neutrophilic leukemia, too many blood stem cells morph into a type of white blood cell known as neutrophils. When too many neutrophils form, the spleen and liver may swell. This disease may progress quickly to acute leukemia.

Chronic eosinophilic leukemia: With chronic eosinophilic leukemia, too many white blood cells, called eosinophils, are produced in the bone marrow. Symptoms may include skin rashes, trouble breathing and impaired mobility.

Myeloproliferative neoplasms, unclassifiable (MPN-U): MPN-Us are myeloproliferative neoplasms that showcase some clinical, morphological or molecular features of myeloproliferative neoplasms, but they don’t fit in any of the subtypes listed above. MPN-Us make up approximately 5 to 10 percent of all myeloproliferative neoplasms.

Risk factors for myeloproliferative neoplasms

Risk factors for MPNs include:

  • Advancing age (these diseases rarely occur in people younger than 50)
  • Gender (males have a higher risk)
  • Prior cancer treatment with chemotherapy (such as mechlorethamine, procarbazine, chlorambucil, cyclophosphamide, ifosfamide, etoposide, teniposide or doxorubicin)
  • Prior cancer treatment with radiation therapy 
  • Genetic syndromes, including Fanconi anemia, Shwachman-Diamond syndrome, Diamond Blackfan anemia, familial platelet disorder, severe congenital neutropenia and dyskeratosis congenita
  • Family history of MPNs
  • Tobacco use
  • Environmental exposures (high-dose radiation, long-term workplace exposure to benzene and certain chemicals used in the petroleum and rubber industries)

What are the myeloproliferative neoplasm symptoms?

MPNs don’t always cause symptoms. Oftentimes, people are diagnosed following a routine blood test. Symptoms may not appear for months or years after a diagnosis.

However, if symptoms do develop, they may include:

  • Frequent headaches
  • Fatigue
  • Bruising
  • Unusual bleeding
  • Blood clots
  • Blurry vision
  • Ringing in the ears
  • Infections
  • Fullness below the ribs, typically on the left side
  • Fever (>100ºF)
  • Itching
  • Anemia
  • Unintentional weight loss in the last six months
  • Night sweats
  • High blood pressure
  • Filling up quickly after eating
  • Abdominal pain

Diagnosing myeloproliferative neoplasms

Testing is the same for all MPNs. In general, diagnosing MPNs involves blood testing and biopsy, including:

  • Routine blood test (also called a complete blood count, or CBC), used to detect abnormal types or numbers of red blood cells, white blood cells or platelets
  • Bone marrow biopsy, which removes and analyzes a small sample of bone marrow
  • Cytogenetic analysis, which looks for chromosomes in blood or bone marrow cells (results can help predict the course and severity of the MPN)
  • Genetic testing, which looks for genetic mutations associated with MPNs
  • Physical exam
  • Abdominal ultrasound

Myeloproliferative neoplasms treatment

Treatment for MPNs is based on the specific type of disease, whether or not it is causing symptoms, and a person’s overall health status. Possible treatments for MPNs include:

Watchful waiting: Not all cases of MPNs will need treatment. Sometimes doctors will monitor for signs of symptoms of progression.

Phlebotomy: A phlebotomy may be used to remove extra red blood cells and reduce the risk of a blood clot.

Platelet apheresis: Platelet apheresis removes platelets from the blood via a separator, and the rest of the blood is then returned to the bloodstream.

Transfusion therapy: Blood transfusions may be used to replace blood cells destroyed by the disease or cancer treatment.

Chemotherapy: These drugs are used to kill cancer cells or stop them from multiplying.

Radiation therapy: Radiation therapy uses high-energy X-rays or other types of radiation to kill cancer cells.

Surgery: A surgeon may remove the spleen (via a splenectomy) if it’s enlarged.

Immunotherapy: Immunotherapy is used to shut down key proteins on immune cells that allow the cancer to go undetected by the body’s immune system. Interferon alfa and pegylated interferon alpha are commonly used immunotherapy drugs for some MPNs.

Targeted therapy: These drugs "target" specific cancer cells without affecting normal cells. Tyrosine kinase inhibitor (TKI) therapy, for example, blocks signals that cancer cells need to grow. Ruxolitinib may be used to treat polycythemia vera and certain types of myelofibrosis.

Stem cell or bone marrow transplant: During this procedure, stem cells are removed from the blood or bone marrow of the patient or a donor, then frozen and stored. The stored stem cells are reinfused so they can grow into healthy blood cells. For some types of MPNs, the procedure is preceded by high-dose chemotherapy.

Some treatments are used to reduce and manage symptoms.

For iron-poor blood or anemia, these medications may be recommended:

  • Erythropoietic growth factors
  • Prednisone
  • Danazol
  • Thalidomide
  • Lenalidomide
  • Pomalidomide, with or without prednisone

In addition, anagrelide therapy may reduce risk of blood clots in patients who have too many platelets in their blood. Low-dose aspirin may also reduce the risk of blood clots. Sometimes clinical trials are available to help treat MPNs.

Staging myeloproliferative neoplasms

A staging system hasn’t been developed specifically for chronic myeloproliferative neoplasms, because the MPN subtypes listed above each behave differently. Knowing the type of MPN helps physicians plan treatment.

While there is no clearly defined staging system for all MPNs, some MPN subtypes are classified into phases. For example, chronic myelogenous leukemia (CML) is classified into phases based on myeloblasts. Immature cells are called myeloblasts (or blasts). Based on the number of blast cells in the blood or bone marrow, CML may be classified as chronic, accelerated or the more severe blast phase. MPN-Us are also classified into phases: early phase MPNs, advanced fibrotic phase MPNs and MPNs with concurrent inflammatory or neoplastic disorders obscuring the clinical-histological picture.

Myeloproliferative neoplasms survival rates

Differences in survival are based on the type of disease:

  • Chronic myelogenous leukemia (CML): According to data from the National Cancer Institute Surveillance, Epidemiology and End Results (SEER) Program, 70.4 percent of people with CML will still be alive five years after their diagnoses. These individuals are expected to have normal lifespans.
  • Essential thrombocythemia (ET): Life expectancy isn’t typically affected. Less than 10 percent of people with ET may develop acute leukemia, according to SEER data analyzed in Leukemia and Lymphoma.
  • Polycythemia vera (PV): Longevity isn’t always affected if the disease is monitored closely. On average, most people with PV live for around 20 years after their diagnosis, according to SEER data analyzed in Leukemia and Lymphoma.
  • Chronic neutrophilic leukemia (CNL): The median survival ranges from six months to 20 years from diagnosis, according to the SEER.
  • Chronic eosinophilic leukemia (CEL): SEER reports that the five-year survival is around 80 percent.
  • Primary myelofibrosis (MF): Unlike other MPNs, MF is more likely to be fatal. The five-year survival rate is 51 percent, according to SEER data analyzed in Leukemia and Lymphoma.

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