Chronic myeloproliferative disorders

Chronic myeloproliferative disorders are a group of slow-growing blood cancers in which the bone marrow makes too many abnormal red blood cells, white blood cells, or platelets, which accumulate in the blood. The type of myeloproliferative disorder is based on whether too many red blood cells, white blood cells, or platelets are being made. Sometimes the body will make too many of more than one type of blood cell, but usually one type of blood cell is affected more than the others.

Normally, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. A lymphoid stem cell becomes a white blood cell. A myeloid stem cell becomes one of three types of mature blood cells:

• Red blood cells that carry oxygen and other substances to all tissues of the body.
• White blood cells that fight infection and disease.
• Platelets that form blood clots to stop bleeding.

In myeloproliferative neoplasms, too many blood stem cells become one or more types of blood cells. The neoplasms usually get worse slowly as the number of extra blood cells increases.

Types

There are 6 types of chronic myeloproliferative disorders: Chronic myelogenous leukemia (CML):Chronic myelogenous leukemia is a disease in which too many white blood cells are made in the bone marrow.

Polycythemia vera:Polycythemia vera is a disease in which too many red blood cells are made in the bone marrow. Symptoms of polycythemia vera include headaches and a feeling of fullness below the ribs on the left side.

Primary myelofibrosis (also called chronic idiopathic myelofibrosis):Primary myelofibrosis is a disease in which abnormal blood cells and fibers build up inside the bone marrow. Symptoms of primary myelofibrosis include pain below the ribs on the left side and feeling very tired.

Essential thrombocythemia:Essential thrombocythemia is a disease in which too many platelets are made in the bone marrow. Patients with essential thrombocythemia may have no signs or symptoms. Signs and symptoms may be caused by essential thrombocytopenia or by other conditions. Check with your doctor if you have any of the following:

• Headache.
• Burning or tingling in the hands or feet.
• Redness and warmth of the hands or feet.
• Vision or hearing problems.

Chronic neutrophilic leukemia:Chronic neutrophilic leukemia is a disease in which too many blood stem cells become a type of white blood cell called neutrophils. Neutrophils are infection-fighting blood cells that surround and destroy dead cells and foreign substances (such as bacteria). The spleen and liver may swell because of the extra neutrophils. Chronic neutrophilic leukemia may stay the same or it may progress quickly to acute leukemia.

Chronic eosinophilic leukemiaL:Chronic eosinophilic leukemia is a disease in which too many white blood cells (eosinophils) are made in the bone marrow. Signs and symptoms of chronic eosinophilic leukemia include fever and feeling very tired.

Chronic myeloproliferative disorders sometimes become acute leukemia, in which too many abnormal white blood cells are made.

Diagnosis

Tests that examine the blood and bone marrow are used to diagnose chronic myeloproliferative neoplasms. The following tests and procedures may be used:

• Physical exam and health history
• Complete blood count (CBC) with differential:
• Peripheral blood smear: A procedure in which a sample of blood is checked for the following:

1. Whether there are red blood cells shaped like teardrops.
2. The number and kinds of white blood cells.
3. The number of platelets.
4. Whether there are blast cells

• Blood chemistry studies
• Bone marrow aspiration and biopsy
• Cytogenetic analysis: A laboratory test in which the chromosomes of cells in a sample of bone marrow or blood are counted and checked for any changes, such as broken, missing, rearranged, or extra chromosomes. Changes in certain chromosomes may be a sign of cancer. Cytogenetic analysis is used to help diagnose cancer, plan treatment, or find out how well treatment is working.
• Gene mutation test: A laboratory test done on a bone marrow or blood sample to check for mutations in JAK2, MPL, or CALR genes. A JAK2 gene mutation is often found in patients with polycythemia vera, essential thrombocythemia, or primary myelofibrosis. MPL or CALR gene mutations are found in patients with essential thrombocythemia or primary myelofibrosis.

Treatment

There are different types of treatment for patients with chronic myeloproliferative neoplasms. Eleven types of standard treatment are used:

• Watchful waiting
• Phlebotomy:Phlebotomy is a procedure in which blood is taken from a vein. A sample of blood may be taken for tests such as a CBC or blood chemistry. Sometimes phlebotomy is used as a treatment and blood is taken from the body to remove extra red blood cells. Phlebotomy is used in this way to treat some chronic myeloproliferative neoplasms.

Platelet apheresis:Platelet apheresis is a treatment that uses a special machine to remove platelets from the blood. Blood is taken from the patient and put through a blood cell separator where the platelets are removed. The rest of the blood is then returned to the patient’s bloodstream.

Transfusion therapy:Transfusion therapy (blood transfusion) is a method of giving red blood cells, white blood cells, or platelets to replace blood cells destroyed by disease or cancer treatment.

Chemotherapy:Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy).

Radiation therapy:Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. External radiation therapy uses a machine outside the body to send radiation toward the area of the body, such as the spleen, with cancer.

Other drug therapy: Prednisone and danazol are drugs that may be used to treat anemia in patients with primary myelofibrosis.

Anagrelide therapy is used to reduce the risk of blood clots in patients who have too many platelets in their blood. Low-dose aspirin may also be used to reduce the risk of blood clots.

Thalidomide, lenalidomide, and pomalidomide are drugs that prevent blood vessels from growing into areas of tumor cells.

Erythropoietic growth factors are used to stimulate the bone marrow to make red blood cells.

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition.

• Imatinib mesylate (Brand name: Gleevec®) Treatment of adult patients with myelodysplastic/myeloproliferative diseases (MDS/MPD) associated with PDGFR (platelet-derived growth factor receptor).

Surgery:Splenectomy (surgery to remove the spleen) may be done if the spleen is enlarged.

Immunotherapy:Immunotherapy is a treatment that uses the patient's immune system to fight cancer or other diseases. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body's natural defenses against disease. This type of treatment is also called biotherapy or biologic therapy.

Interferon: Interferon affects the division of cancer cells and can slow tumor growth. Interferon alfa and pegylated interferon alpha are commonly used to treat certain chronic myeloproliferative neoplasms.

Targeted therapy:Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells. Targeted therapy may cause less harm to normal cells than chemotherapy or radiation therapy do.

Tyrosine kinase inhibitor (TKI) therapy: TKI therapy blocks signals that cancer cells need to grow. Ruxolitinib is used to treat polycythemia vera and certain types of myelofibrosis.

High-dose chemotherapy with stem cell transplant

NIH genetic and rare disease info

• NIH info on Chronic myeloproliferative disorders

Chronic myeloproliferative disorders is a rare disease.

Chronic myeloproliferative disorders Resources
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