What is myelofibrosis?

Myelofibrosis (MF) is a type of bone marrow cancer that affects your body’s ability to produce blood cells. It’s part of a group of conditions called myeloproliferative neoplasms (MPNs). These conditions cause your bone marrow cells to stop developing and functioning the way they should, resulting in fibrous scar tissue.

MF can be primary, meaning it occurs on its own, or secondary, meaning it results from another condition — usually one that affects your bone marrow. Other MPNs can also progress to MF. While some people can go years without having symptoms, others have symptoms that get worse due to scarring in their bone marrow.

Myelofibrosis tends to come on slowly, and many people don’t notice symptoms at first. However, as it progresses and starts to interfere with blood cell production, its symptoms may include:

  • fatigue
  • shortness of breath
  • bruising or bleeding easily
  • feeling pain or fullness on your left side, below your ribs
  • night sweats
  • fever
  • bone pain
  • loss of appetite and weight loss
  • nosebleeds or bleeding gums

Myelofibrosis is associated with a genetic mutation in blood stem cells. However, researchers aren’t sure what causes this mutation.

When the mutated cells replicate and divide, they pass the mutation on to new blood cells. Eventually, the mutated cells overtake the bone marrow’s ability to produce healthy blood cells. This usually results in too few red blood cells and too many white blood cells. It also causes scarring and hardening of your bone marrow, which is usually soft and spongy.

Myelofibrosis is rare, occurring in only about 1.5 out of every 100,000 people in the United States. However, several things can increase your risk of developing it, including:

  • Age. While people of any age can have myelofibrosis, it’s usually diagnosed in those over the age of 50.
  • Another blood disorder. Some people with MF develop it as a complication of another condition, such as thrombocythemia or polycythemia vera.
  • Exposure to chemicals. MF has been associated with exposure to certain industrial chemicals, including toluene and benzene.
  • Exposure to radiation. People who’ve been exposed to radioactive material may have an increased risk of developing MF.

MF usually shows up on a routine complete blood count (CBC). People with MF tend to have very low levels of red blood cells and unusually high or low levels of white blood cells and platelets.

Based on the results of your CBC test, your doctor might also do a bone marrow biopsy. This involves taking a small sample of your bone marrow and looking at it more closely for signs of MF, such as scarring.

You may also need an X-ray or MRI scan to rule out any other potential causes of your symptoms or CBC results.

MF treatment usually depends on the types of symptoms you have. Many common MF symptoms are associated with an underlying condition caused by MF, such as anemia or an enlarged spleen.

Treating anemia

If MF is causing severe anemia, you may need:

  • Blood transfusions. Regular blood transfusions can increase your red blood cell count and reduce anemia symptoms, such as fatigue and weakness.
  • Hormone therapy. A synthetic version of the male hormone androgen may promote red blood cell production in some people.
  • Corticosteroids. These may be used with androgens to encourage red blood cell production or decrease their destruction.
  • Prescription medications. Immunomodulatory medications, such as thalidomide (Thalomid), and lenalidomide (Revlimid), may improve blood cell counts. They may also help with symptoms of an enlarged spleen.

Treating an enlarged spleen

If you have an enlarged spleen related to MF that’s causing problems, your doctor might recommend:

  • Radiation therapy. Radiation therapy uses targeted beams to kill cells and reduce the size of the spleen.
  • Chemotherapy. Some chemotherapy drugs may reduce the size of your enlarged spleen.
  • Surgery. A splenectomy is a surgical procedure that removes your spleen. Your doctor might recommend this if you aren’t responding well to other treatments.

Treating mutated genes

A new drug called ruxolitinib (Jakafi) was approved by the U.S. Food and Drug Administration in 2011 to treat the symptoms associated with MF. Ruxolitinib targets a specific genetic mutation that may be the cause of MF. In clinical trials, it was shown to reduce the size of enlarged spleens, reduce the symptoms of MF, and improve prognosis.

Experimental treatments

Researchers are working on developing new treatments for MF. While many of these require further study to make sure they’re safe, doctors have started using two new treatments in certain cases:

  • Stem cell transplant. Stem cell transplants have the potential to cure MF and restore bone marrow function. However, the procedure can cause life-threatening complications, so it’s usually only done when nothing else works.
  • Interferon-alpha. Interferon-alfa has delayed the formation of scar tissue in the bone marrow of people who receive treatment early on, but more research is needed to determine its long-term safety.

Over time, myelofibrosis can lead to several complications, including:

  • Increased blood pressure in your liver. Increased blood flow from an enlarged spleen can raise the pressure in the portal vein in your liver, causing a condition called portal hypertension. This can put too much pressure on smaller veins in your stomach and esophagus, which could lead to excessive bleeding or a ruptured vein.
  • Tumors. Blood cells can form in clumps outside the bone marrow, causing tumors to grow in other areas of your body. Depending on where these tumors are located, they can cause a variety of different problems, including seizures, bleeding in the gastric tract, or compression of the spinal cord.
  • Acute leukemia. About 15 to 20 percent of people with MF go on to develop acute myeloid leukemia, a serious and aggressive form of cancer.

While MF often doesn’t cause symptoms in its early stages, it can eventually lead to serious complications, including more aggressive types of cancer. Work with your doctor to determine the best course of treatment for you and how you can manage your symptoms. Living with MF can be stressful, so you may find it helpful to seek out support from an organization such as the Leukemia and Lymphoma Society or the Myeloproliferative Neoplasm Research Foundation. Both organizations can help you find local support groups, online communities, and even financial resources for treatment.