Myeloproliferative disorders are a group of cancers characterized by the uncontrolled replication of cells derived from myeloid stem cells. These cells have the potential to become red blood cells, platelets, and some types of white blood cells.

The term “myeloproliferative disorders” was created in 1951, but the World Health Organization (WHO) now classifies these conditions as myeloproliferative neoplasms. They primarily affect older adults, and it’s estimated that there are 1 to 5 cases per 100,000 people per year.

The four most common types of myeloproliferative disorders are:

Read on to learn more about these conditions, including symptoms, treatment options, and outlook.

Your bone marrow contains blood stem cells that have the potential to become two other types of stem cells called myeloid and lymphoid stem cells.

Myeloid stem cells have the potential to become red blood cells, platelets, and some type of white blood cells. Lymphoid stem cells become different types of white blood cells.

Myeloproliferative disorders are a group of cancers that develop in cells derived from myeloid stem cells. There are four main types:

  • Chronic myeloid leukemia (CML). CML is a slow-growing leukemia that starts in immature myeloid cells. About 1 in 526 people in the United States will develop CML in their lifetime.
  • Primary myelofibrosis. Primary myelofibrosis is a condition where bone marrow is replaced with a scar-like material that leads to the abnormal production of blood cells. The condition is estimated to develop in 1.5 people per 100,000 per year in the United States.
  • Essential thrombocythemia. Essential or primary thrombocythemia is a condition where your body produces too many platelets, the cells that help your blood clot. It’s estimated to affect 0.2 to 2.5 people per 100,000 per year.
  • Polycythemia vera. Polycythemia vera is a condition that causes your body to produce an excessive number of red blood cells, which thicken your blood. It’s estimated to affect 2.8 men per 100,000 and 1.3 per 100,000 women per year.

Rarer types of myeloproliferative disorders include:

  • Chronic neutrophilic leukemia (CNL). CNL is an extremely rare condition characterized by the overproduction of white blood cells called neutrophils.
  • Chronic eosinophilic leukemia (CEL). Chronic eosinophilic leukemia is a rare leukemia where your body overproduces white blood cells called eosinophils, which release chemicals in response to infections and allergies. CEL usually progresses slowly. Less commonly, it changes into an aggressive leukemia called acute myeloid leukemia (AML).

Symptoms vary depending on what type of myeloproliferative disorder you have. It’s common not to have any symptoms in the early stages of the disease.

Here’s a look at some potential symptoms for the most common conditions:

CML

Polycythemia vera

Essential thrombocythemia

  • headache
  • dizziness
  • visual changes
  • burning or prickling in limbs
  • fatigue
  • easy bruising
  • stroke-like symptoms
  • enlarged spleen

Primary myelofibrosis

Myeloproliferative disorders are caused by the overproduction of blood cells, but the exact reason they occur isn’t known. They tend to develop in older adults and are more common in males overall. A combination of environmental and inherited genetic factors likely plays a role.

People with a Janus kinase 2 (JAK2) mutation have a higher risk of developing myeloproliferative disorders. Exposure to ionizing radiation and chemicals such as benzene may also increase risk.

The diagnostic process for myeloproliferative disorders starts by contacting a healthcare professional and scheduling an appointment. They will perform a physical exam and evaluate your medical and family history.

If they suspect a blood disorder, they’ll likely order blood tests. Many different blood tests are used to help diagnose myeloproliferative disorders, including:

A definitive diagnosis is usually made with a bone aspiration and biopsy. During this procedure, a doctor uses a long and thin needle to take a sample of your bone marrow for lab analysis.

Allogeneic stem cell transplantation remains the only potential cure for myeloproliferative disorders. This procedure involves receiving donor bone marrow stem cells after receiving a high dose of chemotherapy. It’s usually only an option for people in good overall health.

CML

The main CML treatment is a medication called imatinib. It reduces the production of abnormal white blood cells. If it is not effective, you may be offered similar medications like:

Chemotherapy with or without an allogeneic stem cell transplant may be recommended if you cannot take these medications or you have advanced CML.

Polycythemia vera

Polycythemia vera treatment focuses on reducing the thrombosis risk and providing symptom relief.

People under 60 years old and who do not have a history of blood clots are considered to have a low risk of developing blood clots. Treating polycythemia vera in people at low risk can include:

  • watchful waiting
  • low dose aspirin
  • phlebotomy, a procedure where extra red blood cells are removed with a needle

People at high risk may also take medications to reduce blood cell count.

Essential thrombocythemia

Essential thrombocythemia is usually treated with watchful waiting or low doses of aspirin. People at high risk may also receive medications to lower their blood cell count.

Primary myelofibrosis

People without symptoms are generally not treated. People with symptoms may be treated with the following medications:

They may also be treated with an allogeneic stem cell transplant

Your outlook depends on factors such as:

  • the type of myeloproliferative disorder you have
  • how progressed the condition is
  • your overall health
  • your age

The outlook for CML has improved in recent years with the development of new medications.

According to the National Health Service, it’s estimated that more than 70% of men and 75% of women with CML live at least 5 years following their diagnosis. One large study found that post-diagnosis, about 90% of people with CML treated with imatinib were alive 5 years later, according to the American Cancer Society (ACS).

In a 2018 study, researchers found that following diagnosis:

  • half of people with primary myelofibrosis lived 5.9 years
  • half of people with polycythemia vera lived at least 13.5 years
  • half of people with essential thrombocythemia lived 19.8 years.

Myeloproliferative neoplasms are a group of cancers that cause the overproduction of cells that become red blood cells, platelets, and some types of white blood cells.

Symptoms, treatment options, and outlook depend on which specific condition you have.

If you’re diagnosed with a myeloproliferative neoplasm, your doctor can recommend the best treatment option. If your condition is in the early stages, they may recommend simply waiting to see how it develops.