Myeloproliferative neoplasms (MPNs) are a group of blood cancers that occur when the body creates too many white blood cells, red blood cells, or platelets. “Myelo-” locates the problem in the bone marrow, the part of the body where blood cells are made. “Proliferative” means that certain cells in the bone marrow are reproducing and spreading quickly. Finally, “neoplasms” are cells that grow abnormally.
MPNs are broken down into three main subcategories: essential thrombocythemia (ET), myelofibrosis (MF), and polycythemia vera (PV). MPNs are highly treatable and there are expanding treatment options available as well as clinical trial options that aim to improve further on the current successes.
- MPN Definition
- MPN Symptoms and Causes
- MPN Risk Factors
- MPN Diagnosis and Treatment
- MPN Phases and Survival
What Is the Definition of Myeloproliferative Neoplasms?
Myeloproliferative neoplasms (MPNs) are a group of blood cancers that occur when the body creates too many white blood cells, red blood cells, or platelets, which can lead to circulation problems and other issues, such as anemia in some cases. Over time, these diseases can also accumulate myeloid blasts (very immature white blood cells) which can be found in the blood or bone marrow and signify progression from chronic disease to acute disease. This only happens in a minority of patients.
MPNs are broken down into three main subcategories:
- Essential Thrombocythemia (ET) — overproduction of platelets
- Myelofibrosis (MF) — scar tissue in the bone marrow, caused by the production of abnormal cells and linked to inflammation
- Polycythemia Vera (PV) — overproduction primarily of red blood cells, but can also see increases in white blood cells and platelets
What Are the Symptoms of MPNs?
While MPN symptoms may not be noticeable for some time in many patients (or at all in the case of ET and PV), even years after a diagnosis, here’s a list of what may occur.
- Essential Thrombocythemia: for some, the first symptom of the disease is the presence of a blood clot, which may cause dizziness, swelling of the extremities, throbbing pain in the extremities, fainting, shortness of breath and chest pain.
A transient ischemic attack (TIA), also known as a mini-stroke, can be a sign of the disease as well, as they occur when the blood flow to the brain is temporarily interrupted, which can be caused by a thrombus (blood clot).
- Myelofibrosis: easy bruising and bleeding, bone pain, excessive sweating at night, bloating or fullness beneath your ribs (due to the enlargement of your spleen), and constant fatigue and weakness (due to anemia, which can occur) are all potential signs of MF.
- Polycythemia Vera: some specific symptoms that can occur with PV include bloating or fullness beneath your ribs (due to an enlarged spleen), unusual bleeding (such as nosebleeds or bleeding of the gums), one joint becoming painfully swollen, itchiness following a warm bath or shower, shortness of breath and trouble breathing when lying down, headaches, and numbness or burning in the extremities.
If you notice any unusual changes or have questions about possible MPN symptoms, talk to your doctor.
What Causes MPNs?
Unfortunately, it’s still unclear what exactly causes MPNs, but researchers have discovered specific genetic links to each disease. There are strong connections between mutations to the JAK2 gene (and other “driver mutations” involving MPL and CALR in other patients) – which affects the growth and development of cells – and the development of MPNs. Further research is needed.
What Is the Most Common MPN?
Broadly speaking, all forms of MPNs are rare. Out of the three major types, polycythemia vera (PV) is considered the most common MPN and myelofibrosis (MF) the least common. MF is approximately ten times less common than polycythemia vera (PV) and essential thrombocythemia (ET). In general, the incidence (frequency of new cases) of each of these diseases is approximately one person for 100,000 people and is more common in those over 65 years of age.
Are MPNs Cancer?
This has been and continues to be a debated topic, but most medical experts do recognize MPNs as a type of cancer. MPNs were initially considered myeloproliferative disorders, but the World Health Organization reclassified MPNs as blood cancers in 2008. MPNs are defined by blood cell growth that’s uncontrolled and inappropriate, which fits most organizations' descriptions of cancer.
What Are the Risk Factors for MPNs?
While there are some risk factors that are out of your control when facing MPNs, there are ways to lower your risk. Here’s what you should know.
- For each MPN, age is one of the largest risk factors, as the majority of MPN patients are over the age of 60.
- Women are 1.5 times more likely than men to develop ET, while men stand a slightly greater risk to develop PV than women.
- For PV, exposure to large amounts of radiation and toxic substances may increase your risk of developing the disease.
- Exposure to petrochemicals — which are created through the process of refining petroleum and natural gas — could also put you at greater risk of developing an MPN. Benzene is a particular petrochemical that has been linked to blood cancers. It is present in gasoline and car exhaust, and is used to manufacture certain plastics, rubbers, insecticides, and dyes.
While age and gender are out of your control, you can reduce your risk of developing MPNs by avoiding certain factors in your environment.
Are MPNs Hereditary?
Generally, no. This might seem confusing at first, as genetic mutations have been linked to each of the MPNs, as discussed above. However, these mutations are acquired, not inherited. This means that the changes to DNA occurred during one’s lifetime and are thus not hereditary.
That being said, the MPN Research Foundation notes that some patients may have a familial predisposition to essential thrombocythemia, meaning the disease is more likely to occur among certain families than others. Researchers continue to explore these rare cases to find a connection, but it’s not something most families need to worry about.
How Are MPNs Diagnosed?
Diagnoses for each type of MPN are different. While the process can be a scary one at times, you have the ability to face each MPN with a wide range of sophisticated treatment options. The primary method used to diagnose both essential thrombocythemia and polycythemia vera is through a routine complete blood count. This test can show high platelet counts that suggest ET, and high red blood cell counts (often with increased white blood cells and platelets) in the case of PV.
Both ET and PV can also be diagnosed using a bone marrow biopsy. And while this sounds like an intimidating procedure, it’s likely easier than you think. A fine needle with a hollow center will be used to aspirate (withdraw) a sample of your bone marrow tissue. While you’ll feel some brief pain, a local anesthetic can make the process much more comfortable.
The diagnosis of MF is a bit more complicated, only because it usually involves several different tests. Your doctor can use a complete blood count or bone marrow biopsy in conjunction with a physical examination as well as ultrasound imaging to detect if your spleen is enlarged.
I’ve Been Diagnosed With an MPN, Now What?
The first thing you should do after being diagnosed is to simply pause and take a breath. It’s scary, there’s no doubt about that, but you have many effective and reliable treatment options regardless of the MPN you’re faced with.
After this, you’ll want to talk with your doctor. As is the case with each MPN, it’s possible that you remain symptom-free for many years before needing to start treatment, and in some cases, you may not even need treatment at all. However, it’s important you begin to monitor the disease. This will keep you and your doctor up to date on your options, and in the case of ET, allow you to watch for thrombosis.
What Is the Treatment for MPNs?
If you and your doctor decide that it’s best for you to pursue treatment for your MPN, rest assured you have a range of effective options at your disposal. Treatment varies by MPN.
- Essential Thrombocythemia: the goal of treatment for ET is to reduce the risk of thrombosis, and most therapy options come in the form of prescription or over-the-counter drugs. This may also include taking low-dose aspirin to reduce your risk of clotting. Other medications your doctor may have you use are anagrelide, hydroxyurea, and interferon.
- Myelofibrosis: available drug treatments for MF include fedratinib (Inrebic), which works to reduce the size of your spleen (as it will likely be enlarged) and to inhibit JAK2 mutation. The first drug approved by the FDA specifically for MF treatment is ruxolitinib (Jakafi), which can help to lower blood counts, spleen size, symptoms, and also inhibits JAK2 activity that drives inflammation associated with these diseases. Due to the natural history of this MPN, hematopoietic stem cell transplantation (bone marrow transplant) is a potentially curative option that may be appropriate for some patients.
- Polycythemia Vera: in many cases, therapeutic phlebotomy is used to reduce the number of overall red blood cells present, alongside low-dose aspirin, which prevents platelets from sticking together.
Additional treatment options include the use of hydroxyurea and peginterferon (pegylated interferon) in younger patients and ruxolitinib (Jakafi).
What Are the Phases of MPNs?
The phases of MPNs are defined by the amount of myeloid blasts found in the blood or bone marrow. During the chronic phase the blasts make up less than 10% of the peripheral blood or bone marrow. The accelerated phase is when this amount ranges from 10% to 19%. The blast phase is when there is greater than 20% myeloid blasts in the blood and bone marrow. The National Comprehensive Cancer Network states that it is critical to intervene with treatment when blasts are at 10%.
What Is the Life Expectancy of Someone With an MPN?
While this depends on the specific MPN you’re facing, you should know that the life expectancy is dependent on many factors and is assessed on a case-by-case basis with the use of available prognostic calculators.
In the case of ET, if regular monitoring is performed to prevent thrombosis, your life expectancy is generally not affected at all. In fact, the MPN Research Foundation notes ET patients can expect an “excellent chance of longevity.” This is the case if you're facing PV as well. Monitoring the disease closely is very important though, as PV can lead to the development of other syndromes which can adversely affect you. Attention to the control of the hematocrit is vital to ensuring thrombotic risk reduction.
In the case of MF, while it is possible for the disease to progress quickly, many patients enjoy years without developing serious symptoms. If you work with your doctor and are vigilant about managing symptoms and watching for signs of them, you give yourself a great chance to live a long and productive life.
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Thursday, September 9, 2021
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