Myelofibrosis (MF) is a rare type of cancer that affects the bone marrow. Bone marrow is a spongy area in the center of your bones. When there are cancer cells in the bone marrow, your body has a hard time making healthy blood cells. “Myelo” means your spinal cord, where your bone marrow is. “Fibrosis” means scarring. The bone marrow fills with scar tissue (fibrosis).

MF may also be called primary myelofibrosis, chronic idiopathic myelofibrosis, myelofibrosis with myeloid metaplasia, or agnogenic myeloid metaplasia.

If your provider thinks you may have myelofibrosis, they may order tests, like a bone marrow biopsy to look at your blood cells and molecular testing to look for gene mutations (changes) in the JAK2, CALR, and MPL genes.

How is myelofibrosis diagnosed?

Myelofibrosis is not staged like other cancers. You must meet certain criteria to be diagnosed with myelofibrosis. The World Health Organization (WHO) has made criteria for diagnosing MF. You must meet all 3 major criteria and 1 minor criterion for diagnosis. The criteria for MF can be complex and hard to understand. Your provider will go over any of the criteria listed below that you may have:

Major Criteria

A quick increase and an abnormality of megakaryocytes with either reticulin and/or collagen fibrosis grades 2 or 3 on a scale of 0-3.
Not meeting WHO criteria for ET, PV, BCR-ABL1 positive chronic myelogenous leukemia, myelodysplastic syndromes, or other myeloid neoplasms.
Having a JAK2, CALR, or MPL mutation. If you don’t have one of these mutations, you have another clonal marker or you don’t have reactive myelofibrosis.

Minor Criteria

Anemia (low red blood cell count) not caused by another health issue.
Leukocytosis (higher than normal white blood cell count ≥ 11 x 10⁹/L).
Splenomegaly (enlarged spleen) that can be felt by your provider.
Higher than normal LDH (lactate dehydrogenase) level in the blood. A higher level of this enzyme can be caused by injuries and some diseases.
Leukoerythroblastosis (nucleated red blood cells and immature white blood cells).

How is myelofibrosis treated?

Treatment for MF depends on your symptoms, your age, and your overall health. Treatment may be:

Supportive Care

The goals of supportive care are to:

Help with symptoms of low blood counts.
Improve your quality of life.
Lower your risk of acute leukemia.

Supportive care treatments may be:

Androgen therapy (oxymetholone, danazol): a man made version of male hormones usedto improve anemia.
Erythropoietin: a medication that helps the body to make red blood cells and can improve anemia in some patients.
Hydroxyurea: a medication that is thought to change the synthesis of DNA and is used in the treatment of other blood disorders. It has been shown to decrease the size of the spleen and help control high platelet and WBC counts.
Cladribine: a medication that may be able to stop cells from reproducing by stopping DNA synthesis.
Bisphosphonates (Aredia, Zometa): a type of medication that can help with bone pain and help prevent bone loss.
Splenectomy: the removal of the spleen. An enlarged spleen can be uncomfortable and having it removed can relieve symptoms. Patients with MF and an enlarged spleen, low platelets, and needing frequent transfusions despite drug therapies may get some symptom relief from the removal of their spleen.

Targeted Therapies

Targeted therapy is medications that target the specific genes in MF. Ruxolitinib is currently the only medication with FDA approval for the treatment of MF. Ruxolitinib is a kinase inhibitor. A kinase inhibitor blocks an enzyme (protein) called a kinase. It helps treat MF by stopping cancer cells from multiplying. Other medications in this class are being studied in clinical trials.

Lenalidomide and thalidomide are immunomodulators and are also used in the treatment of myelofibrosis.

Interferon is an immune therapy that works by lowering the amount of unhealthy blood cells and reducing the cytokines that cause scarring (fibrosis) in the marrow. It seems to work best in those with early myelofibrosis secondary to PV or ET. Interferon has side effects that can be hard to manage.

Stem Cell Transplant

The only treatment that can cure myelofibrosis is an allogeneic stem cell transplant (where the bone marrow comes from a donor). Stem cell transplants can lead to serious side effects. For this reason, they are often only done if you are in good health, if you are younger than 60, and if you have a "matched" donor. Stem cell transplants are only done in young patients with high-risk disease.

Clinical Trials

You may be offered a clinical trial as part of your treatment plan. To find out more about current clinical trials, visit the OncoLink Clinical Trials Matching Service.

Making Treatment Decisions

Your care team will make sure you are a part of choosing your treatment plan. This can be overwhelming as you may be given a few options to choose from. It feels like an emergency, but you can take a few weeks to meet with different providers and think about your options and what is best for you. This is a personal decision. Friends and family can help you talk through the options and the pros and cons of each, but they cannot make the decision for you. You need to be comfortable with your decision – this will help you move on to the next steps. If you ever have any questions or concerns, be sure to call your team.

Myelofibrosis: Diagnosis and Treatment