Overview
Myelofibrosis is a kind of bone marrow cancer. Bone marrow is the soft matter inside the bones where blood cells are made. Myelofibrosis causes scarring in the bone marrow. This makes it hard for the bone marrow to make healthy blood cells.
Myelofibrosis sometimes happens on its own. This is called primary myelofibrosis. Sometimes it's caused by another blood cell condition. When this happens, it's called secondary myelofibrosis.
Some people with myelofibrosis have no symptoms and might not need treatment right away. Others with more-serious forms of the disease might need treatment. Treatment for myelofibrosis typically focuses on relieving symptoms.
Myelofibrosis belongs to a group of cancers called myeloproliferative neoplasms. These cancers cause the body to make too many blood cells that don't work right. Myelofibrosis and the other myeloproliferative neoplasms can lead to different types of leukemia. Leukemia is cancer that affects the blood-forming tissues in the body.
Products & Services
Symptoms
Myelofibrosis signs and symptoms may include:
- Feeling tired, weak or short of breath.
- Pain or fullness below the ribs on the left side.
- Easy bruising.
- Easy bleeding.
- Sweating a lot while sleeping, so that you wake feeling covered in sweat.
- Fever.
- Bone pain.
- Feeling full after eating a small amount of food.
When to see a doctor
Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you.
Causes
It's often not clear what causes myelofibrosis. This cancer happens in the bone marrow. Bone marrow is the soft matter inside the bones where blood cells are made.
The bone marrow makes cells called blood stem cells that can become other kinds of cells. When needed, these stem cells can turn into the blood cells that circulate through the body. Blood stem cells can become:
- Red blood cells that carry oxygen to the body.
- White blood cells that help fight infections.
- Platelets that help stop bleeding.
Myelofibrosis starts when blood stem cells in the bone marrow develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy blood stem cells, the DNA gives instructions to turn into blood cells in a controlled way.
In myelofibrosis, the DNA changes give different instructions to the blood stem cells. The changes tell the blood stem cells to make more blood cells than the body needs. The blood cells don't work like healthy blood cells.
Myelofibrosis also causes scarring in the bone marrow. The scarring makes it hard for the bone marrow to make healthy blood cells.
The extra blood cells that don't work right and the bone marrow scarring both can cause too few healthy blood cells in the body. This leads to the symptoms of myelofibrosis. For example, feeling weak and tired can happen if there are too few red blood cells to carry oxygen in the blood.
Healthcare professionals have discovered some genetic changes in the DNA that can cause myelofibrosis, including changes to the:
- Janus kinase 2 gene, also called JAK2.
- Calreticulin gene, also called CALR.
- Thrombopoietin receptor gene, also called MPL.
Your healthcare team might test your cancer cells to see if these changes are present. The results can impact your prognosis and your treatment options.
Risk factors
Although the cause of myelofibrosis often isn't known, healthcare professionals have found some things that might raise the risk. Risk factors include:
- Increasing age. Myelofibrosis can affect anyone, but it's most often diagnosed in people older than 50.
- Another blood cell condition. A small portion of people with myelofibrosis develop the condition as a complication of essential thrombocythemia or polycythemia vera.
- Exposure to benzene. Myelofibrosis has been linked to high levels of exposure to the industrial chemical benzene.
- Exposure to radiation. People exposed to very high doses of radiation have an increased risk of myelofibrosis.
Complications
Complications that may result from myelofibrosis include:
Enlarged spleen
People with myelofibrosis often have an enlarged spleen. The spleen is tucked below the rib cage on the left side of the belly. This organ has many jobs, including storing extra blood cells. In myelofibrosis, extra blood cells made by the bone marrow can build up in the spleen. This causes it to swell. The spleen also might start making blood cells if myelofibrosis causes severe scarring in the bone marrow. This creates more cells that can cause the spleen to swell. When the spleen swells it becomes enlarged. A severely enlarged spleen can cause belly pain and feeling full after eating only a little food.
Portal hypertension
Portal hypertension is the medical term for increased pressure in the portal vein. The portal vein brings blood to the liver. If an enlarged spleen is sending more blood than usual to the liver, it may cause pressure in the portal vein. Pressure in the portal vein can force blood into smaller veins and cause bleeding in the stomach and esophagus.
Growths in other areas of the body
If myelofibrosis makes it hard for the bone marrow to make blood cells, other organs might start making blood cells. The liver and spleen might start making blood cells. Growths of tissue that can make blood cells might form in other areas of the body. This can lead to bleeding in the digestive system, coughing or spitting up blood, compression of the spinal cord, or seizures.
Bleeding complications
Myelofibrosis makes it hard for the body to make healthy platelets. Platelets are blood cells that help stop bleeding. If you have too few healthy platelets, you might bruise more easily. You also could have an increased risk of dangerous bleeding.
Leukemia
Some people with myelofibrosis develop acute myelogenous leukemia. This is a type of blood and bone marrow cancer that often gets worse quickly.