When first diagnosed with a myeloproliferative neoplasm (MPN), many people are left confused about the nature of their condition, how it will impact their lives, and what treatments may be available. MPNs are rare, typically affecting fewer than 6 out of every 100,000 people per year, so not many people have heard of these diseases before. Thus, a newly diagnosed person may have many questions about MPNs, including whether they qualify as cancer.

Are MPNs Cancerous?

The National Cancer Institute defines “cancer” as a disease in which cells uncontrollably divide, producing many new cells and invading surrounding tissues. For some forms of cancer, such as breast or lung cancer, fast cell growth results in the formation of a solid tumor. However rapidly dividing, cancerous blood cells don’t form a hard mass. They instead become so numerous that they clog blood vessels. They also take over the bone marrow, making it hard for the body to produce new blood cells. Cancerous blood cells are not as efficient at carrying out their normal functions, such as delivering oxygen and nutrients, fighting off infection, and properly clotting the blood.

Myeloproliferative neoplasms fit this definition. Certain types of blood cells become so numerous that they take over the blood supply and cause problems throughout the body. Most experts agree that myeloproliferative neoplasms fall under the definition of cancer.

There are three classic types of MPNs, each of which causes an overgrowth of a different type of blood cell. They include:

• Polycythemia vera — This type of MPN is characterized by the overproduction of red blood cells.
• Essential thrombocythemia (ET) — People with ET have high platelet counts.
• Primary myelofibrosis (PMF) — In this MPN, scar tissue builds up in the bone marrow, leading to problems with producing new red blood cells and granulocytes, a specific type of white blood cell.

Other types of MPNs have been identified. These include:

• Chronic myeloid leukemia, also known as chronic myelogenous leukemia
• Chronic eosinophilic leukemia
• Chronic neutrophilic leukemia
• Mastocytosis

What Causes Cancer To Form?

Most cells in the body contain DNA molecules, which are divided up into genes. These genes provide instructions that tell the cell how to work properly. Sometimes, DNA becomes damaged, leading to genetic changes called mutations that interfere with a cell’s normal function. When too many mutations accumulate within a single cell, the cell may become cancerous.

Cancer cells look and behave differently than normal cells in many ways:

• Cancer cells may be more immature than normal cells. They don’t develop fully, so they can’t perform the jobs of a fully matured cell.
• Cancer cells don’t stop growing and dividing. Normal cells receive a signal when it’s time to stop producing new cells, but cancer cells ignore this signal.
• Cancer cells live longer than they should. Normal cells die once they become overly damaged, but cancer cells live on.
• Cancer cells are often ignored by the immune system. Immune cells are supposed to destroy damaged normal cells, but cancer cells can evade this system.

Where Do Gene Mutations Come From?

There are two primary categories of gene mutations: inherited and acquired. Inherited gene mutations are present at birth. These mutations are passed down from one or both of the parents and are found in all cells within the body. Fewer than 10 percent of MPNs are caused by inherited mutations.

Like other blood cancers, MPNs are generally caused by acquired mutations. A single cell may acquire a mutation later in life and pass it on to new cells when it grows and divides. Most MPNs are caused by acquired mutations. It isn’t possible to determine exactly where or how someone got a particular MPN-causing mutation, but some possibilities are:

• Age — As a person gets older, genetic mutations build up in every cell. Usually, the mutations don’t lead to cancer, but a person’s risk does increase as they age.
• Smoking — People who have smoked for many years have a higher likelihood of developing MPNs.
• Obesity — MPNs are more likely to occur in people who have a higher body mass index.
• Chemicals — Those who have been around chemicals such as benzene may have a slightly higher chance of developing myelofibrosis.
• Radiation — Being exposed to high doses of radiation may increase a person’s risk of MPNs.

Learn more about what causes myeloproliferative neoplasms.

Prognosis for Myeloproliferative Neoplasms

Finding out you have cancer is scary, but the good news is that not all cancers are equal. Some have better treatment options and are much more likely to come with a better prognosis (outlook).

MPNs are typically slow-growing. They do not have a cure, but people can often live comfortably with MPNs for many years. However, they tend to have a higher mortality rate than people without MPNs. The most common cause of death is the blood cancer itself. Other causes include infection and heart disease. People with MPNs may be able to work with their health care providers to minimize risk factors that contribute to these other conditions.

Factors That Affect Prognosis

A person’s outlook, or prognosis, is based on several risk factors that can affect how severe the disease is. Some of these include: subtype of MPN, age, leukocytosis, and genetics.

Subtype of MPN

People with essential thrombocythemia have a greater chance of having a close-to-normal life span. However, people with primary myelofibrosis tend to have a shorter life expectancy. Additionally, PMF is more likely than other subtypes to progress to acute myeloid leukemia, a more severe type of blood cancer.

Age

People who are older often have a worse prognosis than those who are diagnosed at a younger age.

Leukocytosis

When people have higher numbers of white blood cells, their MPN is more likely to be severe.

Genetics

MPN cells that have higher numbers of gene mutations have a greater chance of causing severe disease. Additionally, certain specific gene mutations may be more or less likely to lead to a worse prognosis.

Your doctor can help you understand how these factors and others can affect your own outlook. There may be ways of reducing your risk of severe disease.

MPN Next Steps

Like cancer, MPNs don’t have a cure. However, there are treatments for myeloproliferative neoplasms that can help reduce symptoms. Some people with MPNs may not require treatment at all. Depending on an individual’s symptoms, certain cancer treatment options may be available, including chemotherapy or radiation.

MPN research is ongoing. Government organizations and private foundations alike are funding laboratory studies and clinical trials related to MPNs, which help us better understand these cancers and may point to effective new treatments. People with MPNs may continue to have increasingly better treatment options, and as a result, improved quality of life.

Find Your Team

On myMPNteam, the online social network for those living with MPNs, you can gain access to a social support group of people who are facing similar challenges and who understand what you are going through.

Are you or a loved one living with an MPN? Share your ideas in the comments below, or start a new conversation on myMPNteam.