Discovering you have myelofibrosis (pronounced MY-eh-loh-fy-BROH-sis), a disease that many people have never heard of, can be overwhelming. Learning as much as you can about this rare disease and its treatment will empower you to make the decisions that are ahead. And know that you do not have to go through this alone. You will be surrounded by a multidisciplinary team of doctors and specialists who will provide support and guidance.

Myelofibrosis is a hematologic (blood) cancer that falls into the category of myeloproliferative neoplasms (MPNs), a group of cancers that affect the bone marrow. Following are the three main types of MPNs and their defining characteristics.

  • Essential thrombocythemia (ET) — too many platelets
  • Polycythemia vera (PV) — too many red blood cells
  • Primary myelofibrosis — too many fibroblasts, which are connective tissue cells that make and secrete collagen proteins 

This content focuses on primary myelofibrosis and its treatment, side effects and ongoing supportive care.

Understanding Myelofibrosis

This rare cancer begins in the bone marrow when abnormal blood stem cells produce immature cells that grow quickly and take over. The immature cells become fibrous and fill the bone marrow with scar tissue. As a result, not enough normal blood cells can be made, and other organs, such as the spleen or liver, may try to compensate and become enlarged in the process.

Bone marrow is the soft, spongy center of some bones. It is where blood is created and is made up of blood stem cells, more mature blood-forming cells, fat cells and supporting tissues. Blood stem cells can become:

  • Red blood cells that carry oxygen from the lungs to other parts of the body
  • White blood cells that fight off infection and other foreign intruders in the body
  • Platelets that help blood to clot and to stop bleeding

Both ET and PV can progress to myelofibrosis. When myelofibrosis develops from ET or PV, it is known as secondary myelofibrosis, which may also be referred to as either post-ET myelofibrosis or post-PV myelofibrosis. When myelofibrosis develops spontaneously, it is known as primary myelofibrosis. Although myelofibrosis is considered a chronic (slow-growing) blood cancer, in some cases it can transform to acute myeloid leukemia.

Myelofibrosis affects the development of red blood cells, white blood cells and platelets. They are often misshapen and immature so they cannot perform their normal function. As a result, there are low levels of red blood cells and too many white blood cells.

People may or may not have symptoms at diagnosis, and the progression of myelofibrosis can vary from person to person. The most common symptoms are fatigue, feeling full quickly, weight loss, fever, bone pain, night sweats, itching (especially after bathing), abdominal discomfort or bloating. In the absence of symptoms, blood tests may indicate abnormal amounts of cells that can prompt the need for further testing.

Classifying and Determining Risk

Multiple tests are used to diagnose myelofibrosis and to rule out other types of blood and bone marrow cancer that have similar features. Testing typically includes a physical exam, a symptom survey, blood tests, a bone marrow biopsy, and chromosome and specific gene testing, among others. Imaging studies to evaluate the size of the liver and spleen are also commonly included in the initial evaluation.

Along with examining your test results, your doctor will use a prognostic scoring system that determines your prognosis (outcome) based on risk factors. You will be placed into a risk category to better treat your individual symptoms.

The Dynamic International Prognostic Scoring System (DIPSS) Plus, which scores risk during treatment, is commonly used. It divides risk into four tiers: low risk, intermediate-1 risk, intermediate-2 risk and high risk. You will be treated based on your risk score and other factors.

Multiple prognostic scoring systems exist. If you are unsure which one your doctor used, ask. Some differentiate between whether the patients are asymptomatic or symptomatic.