Myeloproliferative neoplasms (MPNs), formerly known as myeloproliferative diseases, are a rare type of blood cancer. MPNs cause the overproduction of blood cells by the bone marrow, including white blood cells, red blood cells, or platelets. The overproduction of cells can compromise blood flow and cause the various signs and symptoms common in MPNs.
Types of Myeloproliferative Neoplasm
There are three main types of MPN also called “classical MPNs:” essential thrombocythemia (ET), myelofibrosis (MF), and polycythemia vera (PV). Some types of leukemia, such as chronic myelogenous leukemia (CML), are also considered a type of MPN.
Essential Thrombocythemia (ET)
Essential thrombocythemia (ET) makes up approximately 25 percent of MPN diagnoses. ET causes the body to produce too many platelets, which can lead to abnormal clotting (thrombosis). Platelets are the element of blood responsible for the part of the blood needed for clotting.
Polycythemia Vera (PV)
Polycythemia vera (PV) is the most common MPN, making up 45 percent of all MPN diagnoses. PV causes an overproduction of red blood cells, whose role it is to carry oxygen through the body. Too many red blood cells can make the blood thicker and slow down its passage through the body’s circulatory system. Sometimes, PV can cause an overproduction of white blood cells and platelets as well.
Myelofibrosis (MF) is a type of MPN that disrupts the proper production of blood cells and that causes scar tissue inside the bone marrow, where blood cells are produced. Primary myelofibrosis (PMF) develops independently. Secondary myelofibrosis (SMF) develops as a result of another bone marrow disorder, including other MPNs such as PV or ET. Between 10 and 20 percent of people with PV see their PV progress to MF.
MPN Signs and Symptoms
Common MPN symptoms include:
- Extreme fatigue
- Abnormal bleeding and clotting
- Bone pain, which can be excruciating or debilitating
- Itching severe enough to interfere with day-to-day life
- Enlarged spleen, which may feel like pain or fullness on the left side, below the ribs
- Anxiety and depression
MPNs are known to drastically and negatively impact a person’s quality of life.
MPNs are usually chronic, progressive conditions, meaning they worsen over time and there isn’t a cure. Hence, the primary MPN treatment goals seek to manage symptoms, improve a person’s quality of life, and to slow down disease progression. MPN treatments also seek to prevent complications such as blood clots and cardiovascular issues.
Targeted therapies, specifically JAK inhibitors, are the first-line treatment for most classical MPNs. The two targeted drugs approved by the FDA for MPN treatment are Ruxolitinib and Fedratinib.
The only potential cure for MPNs is an allogeneic haematopoietic stem cell transplant (ASCT). ASCT isn’t a guaranteed cure and it comes with a lot of risks, so it is usually only recommended for younger people with MF.
Prognosis of MPNs
The average years of survival estimated for MPNs are 33 years for ET and 24 years for PV. The prognostic estimate for MF is 15 years for people who are diagnosed when they’re younger than 60 years.