Myelofibrosis occurs in about 1.5 out of every 100,000 people in the United States annually. Men, women and children can all be affected and more people are being diagnosed at an earlier age.
Myelofibrosis is a type of chronic blood cancer that can occur on its own or as the result of another bone marrow disorder. It is called primary myelofibrosis when it occurs on its own and secondary myelofibrosis when it converts from another disorder.
In primary myelofibrosis, a genetic mutation in the blood-forming stem cell disrupts the body’s production of normal blood cells, including the red blood cells, white blood cells, and platelets. The abnormal cells begin to take over the normal cells causing a disruption in the function that those cells serve. Extensive scarring in the bone marrow occurs know as fibrosis. Myelofibrosis is often diagnosed by an enlarged spleen and abnormal blood test results.
The results of a blood test or complete blood count (CBC), that suggest a diagnosis of MF include:
- A decrease in the number of red blood cells (anemia) below the normal range
- An increase or decrease in the number of white blood cells
- An increase in platelets above the normal range
- A mild to moderate decrease in platelets below the normal range
Other symptoms of myelofibrosis:
- Fatigue, weakness, shortness of breath – mostly due to anemia
- Pain or fullness below the ribs on the left side as a result of an enlarged spleen – splenomegaly
- Enlarged liver – hepatomegaly
- Pale skin
- Easy bruising or bleeding, due to a decrease in the platelet count – thrombocytopenia
- Flat, red, pinpoint spots under the skin caused by bleeding – petechiae
- Night sweats
- Frequent infections due to low white blood cell count – neutropenia
- Bone or joint pain
- Weight loss
- Itching – pruritus
MF develops when a genetic mutation occurs in blood stem cells. The cause of the gene mutation is unknown. Between 50 and 60 percent of people with MF have a mutation of the Janus kinase 2 (JAK2). Researchers are investigating other possible gene mutations in MF. Visit www.mfchallenge.org for more information on MF.
Treatments for Myelofibrosis
There are various drugs used to treat MF. Many are used to slow the disease process or control the effects of the disease. There are side affects with many drugs and those should be reviewed with you and your doctor or nurse before starting any treatment.
Chemotherapy: These drugs kill cancer cells that divide rapidly. They also attack other fast growing cells in the body, such as fingernails, toenails and hair. These drugs may be given orally or intravenously.
JAK2 Inhibitor: This class of drug inhibits enzymes called JAK1 and JAK2, which are involved in regulating blood. The first JAK inhibitor specifically for MF has been approved by the FDA and others are currently in clinical trials. JAKAFI (developed by Incyte; also called ruxolitinib) is the first drug specifically for MF, was approved by the FDA in 2011. Taken orally, JAKAFI inhibits the activity of JAK2 and the related protein JAK1. JAKAFI reduces symptoms in many MF patients and showed a reduction in the level of pro-inflammatory cytokines in the blood. JAKAFI inhibits both normal JAK1 and JAK2 and JAK2V617F.
Immunomodulators (IMiDs): The drugs in this class work against cancer cells by affecting the functions of the immune system.
Androgen therapy: These drugs are synthetic forms of male hormones and promote red blood cell production.
Recombinant erythropoietin: This treatment helps regulate red blood cell production.
Glucocorticoids: Also known as “steroids,” these drugs are used to treat anemia in MF patients.
Biophosphonates: These drugs are used to prevent bone loss in cancer patients and they may relieve bone pain as well as increase blood counts in MF patients.
Anagrelide hydrochloride: This drug is given orally and may be used in MF patients who have an extremely high platelet count.
Radiation Therapy: Radiation therapy can help reduce the size of the spleen and can reduce bone pain in tumors outside the bone marrow.
Surgical Removal of the Spleen (Splenectomy): If your spleen is so enlarged that is causing complications and other interventions have not been successful, some patients have splenectomies. You and your physician will consider all the risks and benefits of your particular situation and determine it is an option.
Stem Cell Transplantation: This is the only treatment known to cure MF even though the risks can be very high. Many factors should be considered with your healthcare team.
Types of stem cell transplants:
- Allogenic stem cell transplant: The patient receives high doses of chemotherapy or radiation to destroy the diseased bone marrow. The donor stem cells (from a donor match) are then infused into the patient.
- Non-myeloblative stem cell transplant: Uses lower doses of chemotherapy or radiation prior to the infusion of donor cells. This type of transplant is often used in older, sicker patients who may not be eligible for an allogenic transplant.