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If you’re living with paroxysmal nocturnal hemoglobinuria (PNH), you may be wondering if PNH is a type of cancer. Although PNH shares many similarities with blood cancers, it’s not a type of cancer. What are the similarities between PNH and blood cancers? What are the differences? This article will explore seven facts about PNH and blood cancers.
PNH is a rare blood disorder in which the immune system breaks down red blood cells, releasing an excess of the red blood cell protein, hemoglobin. Your body gets rid of the excess hemoglobin through your urine, which is why bloody urine is the most common symptom. PNH also affects white blood cells and platelets, so all types of blood cells are involved.
Blood cancer is a broad category of cancer types that includes three main categories: leukemia, lymphoma, and myeloma. Blood cancers can affect any of the three types of blood cells: platelets, red blood cells, or white blood cells. In lymphoma, white blood cells make too many copies of themselves. In other blood cancers, like leukemia, the cells that develop into blood cells stop developing into mature blood cells. These cells start making too many copies of themselves in the middle stage of development, resulting in immature forms that can’t function properly.
The bone marrow is the squishy or foamy material at the center of the bones. Bone marrow makes and stores specialized cells that turn into blood cells. In PNH, problems in the bone marrow make blood cells that are easily broken down by the immune system.
Changes in the bone marrow also cause leukemia. However, in leukemia, the specialized cells in the bone marrow aren’t able to properly develop into mature blood cells.
PNH and blood cancers are usually caused by mutations (changes) in genes that occur throughout life. They are considered acquired rather than inherited because the person wasn’t born with that mutation. Acquired mutations can still affect other cells. When the cells make copies of themselves, they pass along those mutations.
PNH and blood cancers are usually caused by mutations in genes that occur throughout life.
People with PNH have a mutation in a gene in their bone marrow cells. The gene is called PIGA. When the cells in the bone marrow have a PIGA gene mutation, these cells develop into red blood cells that don’t have a protein to protect them from breakdown by the immune system. When the red blood cells lack this protein, the immune system destroys the red blood cells, a process known as hemolysis.
Genetic mutations can also cause blood cancers, but they are in different genes and cause different effects. In leukemia, many different mutations in bone marrow cells can cause the cells to stop developing into mature blood cells. The mutations ultimately cause a certain cell type to divide too quickly. These abnormal cells multiply so much that they take over the bone marrow, stopping normal cells from forming. This process is known as bone marrow failure.
PNH and leukemia have some, but not all, of the same symptoms. Common symptoms of PNH are:
The most common leukemia symptoms that are also seen in people with PNH are:
There are also leukemia symptoms that are different from PNH. They include:
The differences in symptoms between the two conditions can help you and your doctor feel confident about your diagnosis.
PNH and blood cancers don’t necessarily affect people of the same age, sex, and ethnicity. PNH often affects different groups of people than blood cancers do.
PNH often affects different groups of people than blood cancers do.
Although PNH can affect people of any age, most people with PNH are diagnosed in their 30s. Most blood cancers, on the other hand, develop later in life. It’s common for myeloma, types of lymphoma, and most types of leukemia to develop after the age of 65. Acute lymphoblastic leukemia is an exception that usually develops in children and people under 40.
PNH affects males and females equally, although some studies suggest females are more susceptible to the condition. Most blood cancers are more likely to occur in males, according to Cleveland Clinic.
People of all ethnicities can be diagnosed with PNH. However, it may be more commonly diagnosed in people from East Asia and Southeast Asia. Myelomas are more common in Black people than white people. Leukemias are more common in white people than Black people.
Even though PNH and blood disorders generally affect different populations, PNH can increase your risk of developing leukemia. Between 3 percent and 5 percent of people with PNH develop leukemia. As reported in the journal Leukemia, people with PNH are more likely to develop a specific type of leukemia, acute myeloid leukemia, than the general population. This makes having PNH a significant risk factor.
Between 3 percent and 5 percent of people with PNH develop leukemia.
PNH can also increase your risk of developing myelodysplastic syndrome, which is a group of disorders caused by blood cells that don’t mature properly. Although PNH may increase your risk of developing certain conditions, the risk is low. Just because more people with PNH develop these conditions doesn’t mean you will.
Some, but not all, of the treatments used in PNH are also used to treat blood cancers.
PNH and some blood cancers may use bone marrow transplants as a treatment option. These are procedures where a person who has a problem with their bone marrow is given healthy bone marrow cells either from themselves or another donor. For PNH, bone marrow transplants can cure the condition, although they also come with risks.
PNH and blood cancers may use therapies that act on the immune system, but the way these drugs work on the immune system is different.
In PNH, part of the immune system works overtime to break down red blood cells. This part of the immune system is called the complement system. Therapies for PNH that affect the immune system work by stopping parts of the complement system. They are called immunosuppressive drugs. Some of the drugs that suppress the complement system include:
Treating PNH can also include supportive measures to improve hemoglobin levels such as hormonal therapies, blood transfusions, iron replacement, and folic acid. Because patients with PNH are more likely to develop blood clots, they may also receive blood thinners.
In addition to bone marrow transplants, there are plenty of other treatments for blood cancers. Unlike the therapies that block the immune system for PNH treatment, blood cancer treatment often involves immunotherapies that help your immune system fight off cancer cells. Chemotherapies, drugs that kill rapidly multiplying cells, are common therapies for blood cancers. Radiation therapies are also frequently used in blood cancer treatments but not in PNH treatment.
On myPNHteam, the social network for people with paroxysmal nocturnal hemoglobinuria and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with PNH.
Have you wondered whether PNH is a type of cancer? What questions do you have about the relationship between PNH and blood cancers? Share your experience in the comments below, or start a conversation by posting on your Activities page.
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Fatima Sharif, MBBS, FCPS
graduated from Aga Khan University, Pakistan, in 2017 after completing medical school.
Learn more about her here.
Hannah Actor-Engel, Ph.D.
is a multidisciplinary neuroscientist who is passionate about scientific communication and improving global health through biomedical research.
Learn more about her here.
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