Multiple myeloma is a blood and bone marrow cancer that affects plasma cells. These are a type of white blood cell that helps protect the body from infections.

In multiple myeloma, abnormal plasma cells accumulate in the bone marrow, where they crowd out healthy blood cells. This can lead to widespread health complications.

Doctors still do not know what causes multiple myeloma. However, some people are more likely to develop the disease than others, including those who have a first-degree relative with the disease.

This article outlines whether multiple myeloma runs in families, and lists some additional risk factors for the disease. We also cover the symptoms and complications of the disease, as well as some of the treatment options available.

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Experts still do not know the cause of multiple myeloma (MM). However, several genome-wide association studies have found 24 gene variants associated with the disease. Some of these variants may be passed on from one generation to the next.

According to the International Myeloma Foundation, around 5-7% of people with myeloma have a close relative who has myeloma or the condition monoclonal gammopathy of undetermined significance (MGUS).

In MGUS, the plasma cells make abnormal proteins. Although MGUS is benign, around 1% of people who have the condition go on to develop MM.

However, the American Cancer Society (ACS) notes that most people who develop MM do not have any relatives with the condition.

Certain factors increase a person’s risk of developing MM. Some examples are:

Age

Multiple myeloma typically occurs in people who are over 60 years of age. The average age at diagnosis is 70 years. Only 2% of cases occur in people below the age of 40, and less than 1% of these occur in people younger than 35.

Gender

MM is slightly more common among males than among females.

Race

The disease is twice as common among Black people than it is among people of other ethnicities. It is also twice as deadly in Black people than in white people.

Family history

People who are first-degree relatives of those with MM, MGUS, and certain other cancers are at increased risk of developing MM.

Obesity

Obesity is a risk factor in several cancers, including MM. Obesity can drive the progression of MM by increasing:

  • the number of fat cells present
  • the size of fat cells that are present
  • the levels of certain molecules called adipokines that these cells secrete

When fat cells secrete adipokines at controlled levels, they can have protective properties. However, secreting higher levels of these molecules creates an environment within the bone tissue that fuels MM cell development.

Having certain cancers and conditions

Certain pre-existing conditions can increase the risk of MM. Examples include MGUS and solitary plasmacytoma (SP). In SP, a build-up of abnormal plasma cells forms a tumor in a bone or in soft tissue.

Exposure to radiation and chemicals

Exposure to certain substances or chemicals can increase the risk of MM. Some examples include:

  • radioactive substances
  • asbestos
  • benzene
  • pesticides

Multiple myeloma accounts for 1–2% of all cancers and comprises 10% of all blood or hematological cancers.

The ACS estimates that around 34,920 Americans will receive a diagnosis of myeloma in 2021. At present, the risk of someone in the United States developing multiple myeloma in their lifetime is 1 in 132.

Multiple myeloma often does not cause symptoms until it reaches advanced stages. Most of the time, people discover the disease in a blood or urine test for a different issue.

Some symptoms are non-specific and a person or doctor may mistake them for symptoms of a different condition. Examples include:

Asymptomatic (non-symptomatic) MM is called smoldering MM.

Most of the time, the above symptoms will not indicate MM. However, a person who is concerned about any of the above symptoms should make an appointment with their doctor.

Late symptoms often present at the time of diagnosis. They may include:

  • bone pain
  • mental fogginess or confusion, likely due to elevated levels of calcium in the blood, or hypercalcemia
  • weight loss
  • paralysis or numbness/tingling in the legs, which can happen if a MM bone lesion compresses the spine
  • kidney problems

As MM proliferates, it can lead to a shortage of normal blood cells. This can result in:

Anemia

Anemia is the medical term for a lack of healthy red blood cells. These cells help deliver oxygen to the body’s tissues.

In anemia, body tissues do not receive adequate oxygen to function. This can lead to:

Thrombocytopenia

Thrombocytopenia is the medical term for low levels of platelets in the blood. Platelets are cell fragments that help to form blood clots and stop bleeding.

Thrombocytopenia impairs the blood’s ability to clot, which may result in excessive bruising and bleeding.

Leukopenia

Leukopenia is the medical term for a reduced number of leukocytes in the blood. Leukocytes are a type of white blood cell that helps to fight infections and disease.

Leukopenia may not cause any symptoms. However, a person who develops an infection as a result of leukopenia may develop the following symptoms:

There is no cure for MM, but treatments can help control tumor growth and slow its progression. The type of treatment a person receives will depend on several factors, including:

  • the stage of the cancer
  • whether the person is experiencing symptoms or complications of MM
  • the person’s overall health

People with MM who do not present with symptoms will not receive treatment. However, they will receive close monitoring from their medical team.

The initial treatment for people who present with symptoms may be intensive or non-intensive, depending on their health status. For people in otherwise good health, doctors may recommend high-dose chemotherapy followed by a stem cell transplant. For people who are in poor overall health, doctors may recommend low-dose chemotherapy and corticosteroids.

Drugs

Doctors typically use a combination of two to three drugs to treat MM. These include:

  • Chemotherapy drugs: These drugs destroy cancer cells or control their growth. Examples include cyclophosphamide and etoposide.
  • Corticosteroids: Corticosteroids help destroy cancer cells and make chemotherapy more effective. They can be given alone or with another drug. Examples of steroids include prednisolone and dexamethasone.
  • Targeted drugs: These drugs target specific cancer genes and proteins that promote cancer survival and growth. Targeted drugs include:
    • proteasome inhibitors
    • histone deacetylase (HDAC) inhibitors
    • monoclonal antibodies
    • nuclear export inhibitors
    • antibody-drug conjugates
  • Immunomodulatory drugs: These drugs stimulate a person’s immune system and prevent any new blood vessel formation that can promote cell growth. Examples include thalidomide and lenalidomide.

Surgery

Surgery may be an option for people who have MM that is not in the bone and is localized to one particular part of the body.

Surgery may also be necessary to prevent weakened bones from breaking, or to repair existing bone fractures.

Radiation therapy

Radiation therapy can help to:

  • reduce bone pain
  • treat bones that are weakened and close to breaking
  • treat bones that are not responding to chemotherapy treatment

Stem cell transplant

Stem cells are special cells that are produced in the bone marrow. They can turn into different types of blood cells.

A stem cell transplant generates healthy stem cells to replace diseased stem cells. The stem cells that a doctor uses for the transplant will derive either from the person’s own body (autologous) or from a donor (allogeneic).

In people who are otherwise healthy, stem cell transplants typically follow a high-dose chemotherapy protocol.

CAR T-cell therapy

Chimeric antigen receptor t-cell (CAR T cell) therapy is relatively new for MM, having recently received FDA approval for use when multiple other treatments have failed to help a patient.

This kind of immunotherapy helps boost a person’s immune system to fight off cancer. In CAR T cell therapy, a person’s lab-altered T-cells are infused into their body to help attack cancer cells.

Supportive care

People may also receive treatments to help alleviate their symptoms and improve their quality of life. Examples of such treatments include:

  • bone modifying drugs to prevent bone cells called osteoclasts from destroying the bones
  • blood transfusions to help reduce fatigue caused by anemia
  • plasmapheresis, which is a procedure that can help stabilize blood plasma levels

After the initial treatment

After initial treatment, a person will continue to take medications to help kill any remaining cancer cells in their body.

A person will also take drugs long-term to help delay the return of MM and prevent relapse.

MM has a 5-year relative survival rate of 53%. The following factors are associated with a poorer disease outlook:

  • high serum β2-M, low albumin, and high lactate dehydrogenase (LDH)
  • presence of chromosomal abnormalities
  • poor kidney function
  • old age
  • poor overall health

Being in the latter stages of cancer and having a high plasma cell labeling index (PCLI) are also associated with poorer outcomes, since this means that the cancer is rapidly progressing.

Multiple myeloma is a type of blood and bone marrow cancer that affects plasma cells. As the disease progresses, abnormal plasma cells crowd out healthy blood cells, which can lead to complications and associated symptoms.

Experts are unsure of what causes MM, though genetic factors are likely to play a role. Research suggests that a person is at increased risk of developing MM if they have a first-degree relative who has the disease. However, most people who have MM do not have any relatives who have the disease.

Although there is currently no cure for MM, there is a range of treatments that can help put the disease into remission and increase overall survival times.