Myelofibrosis is a rare blood cancer where scar tissue forms in your bone marrow. It’s a type of chronic leukemia that involves too many abnormal blood cells being made. Eventually, these cells can replace normal cells. Treatment goals mainly involve managing symptoms and conditions that arise, including anemia and an enlarged spleen.
Myelofibrosis is a rare type of blood cancer where your bone marrow (the soft, spongy tissue inside of your bones) is replaced by fibrous scar tissue. It’s a form of chronic leukemia and a myeloproliferative disorder. Myeloproliferative disorders involve too many blood cells getting made in your bone marrow — where blood cells get made.
Your bone marrow produces immature blood-forming cells called stem cells that may develop into red blood cells, white blood cells or platelets. With myelofibrosis, a change (mutation) in a stem cell’s DNA causes the cell to become defective, or a cancer cell, instead. The cell multiplies, passing the mutation onto new cells.
Over time, more abnormal cancer cells are produced. Some of these cells create inflammation that causes scar tissue to form in your bone marrow. The scarring and the excess cancer cells can prevent your bone marrow from making healthy blood cells.
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There are two types of myelofibrosis:
Myelofibrosis is rare, with about 1.5 cases reported per 100,000 people each year in the United States. It affects people regardless of sex. People of any age can have myelofibrosis, although it’s more likely to be diagnosed in people over 50. Children with myelofibrosis are usually diagnosed before age 3.
The abnormal blood cell production can lead to a variety of conditions, including:
In about 12% of all cases, primary myelofibrosis progresses to acute myeloid leukemia, a very aggressive form of blood cancer.
Scientists don’t know what causes myelofibrosis, but they know it’s associated with DNA changes in specific genes. Proteins called Janus-associated kinases (JAKs) play a role in myelofibrosis. JAKs regulate the production of blood cells in bone marrow by signaling the cells to divide and grow. If the JAKs become overactive, too many or too few blood cells will be produced.
About 60% to 65 % of people with myelofibrosis have a mutation in the JAK2 gene. Another 5% to 10% have a mutation in the myeloproliferative leukemia (MPL) gene. A mutation called calreticulin (CALR) accounts for approximately 20% to 25 % of myelofibrosis cases.
You’re at increased risk of myelofibrosis if:
Myelofibrosis progresses slowly, so you may not have symptoms for many years. About one-third of people don’t show symptoms during the disorder’s early stages.
When they arise, the most common symptoms of myelofibrosis are severe fatigue (resulting from anemia) and an enlarged spleen. Symptoms may include:
A healthcare provider (oncologist) will perform a physical exam and ask about your medical history, including any symptoms you’re experiencing. They’ll check for signs of an enlarged spleen and anemia.
They’ll perform various tests to rule out other conditions and confirm your diagnosis.
You may need additional tests to confirm your diagnosis, including:
You don’t need treatment unless you’re experiencing symptoms. Still, your healthcare provider will monitor your condition even if you don’t require immediate treatment.
Jakafi® (ruxolitinib), Inrebic® (fedratinib) and Vonjo® (pacritinib) are U.S. Food and Drug Administration (FDA)-approved drugs for treating intermediate or high-risk myelofibrosis. All three drugs are JAK inhibitors that reduce overactive Janus-associated kinase (JAK) signaling. They help relieve some of the symptoms associated with myelofibrosis, including an enlarged spleen, night sweats, itching, weight loss and fever.
For most people, treatment goals are to manage conditions associated with myelofibrosis, including anemia and splenomegaly.
Treatments for anemia include:
Treatments used to manage an enlarged spleen include JAK inhibitors, immunomodulators and chemotherapy drugs. In severe cases, you may need to have your spleen removed (splenectomy), or you may need radiation therapy to your spleen.
You may need radiation therapy to treat extramedullary hematopoiesis (abnormal growth of stem cells outside of your bone marrow).
Allogeneic hematopoietic cell transplantation (HCT) is a potential cure, but it’s a risky procedure that may not be an option for everyone.
The procedure involves replacing abnormal blood cells with healthy cells from a donor. Before the transplant, you’ll receive chemotherapy or radiation therapy to destroy your diseased cells so the new cells from the donor will take over.
HCT carries a high risk of complications and is only suitable for certain people. The risk of a complication is higher for people with other medical conditions. Various factors will determine whether you’re a candidate, including your age, the severity of your symptoms and your likelihood of success.
Myelofibrosis is aggressive cancer with a median survival rate of six years. A median is a midpoint, which means that some people live less than six years, and about the same number of people live longer than six years.
Multiple factors affect your prognosis, including:
Talk with your provider about what your diagnosis means for your experience of the disease.
Ask your healthcare provider if you could benefit from palliative care. Palliative care teams may include doctors, nurses, social workers and other care specialists who provide resources to help you navigate your illness. They provide a support network that complements the care you receive from your oncologist. Palliative care specialists can improve your quality of life as someone navigating a cancer diagnosis.
A note from Cleveland Clinic
Myelofibrosis is a rare type of blood cancer where your bone is replaced by fibrous scar tissue. It’s a serious condition that requires careful monitoring and/or treatment. Depending on your situation, you may go several years with no symptoms. In other instances, symptoms may progress quickly, making it harder to carry out your daily routine. Treatments can help manage symptoms that may be interfering with your day-to-day life. In the meantime, ask your provider to connect you with resources that can help you navigate the changes you may be experiencing. Palliative care and support groups are useful options when adjusting to a cancer diagnosis.
Last reviewed by a Cleveland Clinic medical professional on 08/22/2022.
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