Multiple myeloma is sometimes considered a type of bone cancer. It develops in white blood cells called plasma cells that are found in your bone marrow.

Multiple myeloma, also shortened to myeloma, develops when plasma cells replicate out of control and crowd out healthy blood cells.

Cancerous plasma cells can form tumors in your bone marrow that make your bones weaker. Bone pain has been reported as a symptom of myeloma in more than half of people in some research.

A closely related condition called solitary plasmacytoma can cause a single tumor to form in your bone marrow. Solitary plasmacytoma progresses to myeloma in about 70% of cases.

Multiple myeloma most commonly develops in older adults. The average age of diagnosis with multiple myeloma is 66 to 70 years old.

Myeloma can cause tumors to form in bones throughout your body. Some but not all organizations classify multiple myeloma as bone cancer.

According to the American Academy of Orthopaedic Surgeons, multiple myeloma is the most common primary bone cancer. Primary means it starts in bone tissue as opposed to spreading from another body part.

However, the American Cancer Society doesn’t consider multiple myeloma a primary bone cancer because it starts in plasma cells inside the bone marrow. They consider multiple myeloma a plasma cell cancer.

Multiple myeloma is closely related to several other conditions characterized by the abnormal replication of plasma cells such as:

  • Monoclonal gammopathy of undetermined significance (MGUS): MGUS is a precancerous condition that has about a 1% chance of turning into multiple myeloma each year.
  • Plasmacytoma: Plasmacytoma is a type of cancer that’s considered an intermediate phase between MGUS and multiple myeloma.

Plasmacytoma and your bones

The most common type of plasmacytoma is called solitary plasmacytoma. Solitary plasmacytoma is very rare. It’s estimated to affect about 15 people per 10 million.

Solitary plasmacytoma is characterized by a single tumor, often in bone, without other classic symptoms of myeloma such as anemia or the presence of M-protein.

Multiple myeloma can cause bone symptoms such as:

  • bone pain, most often in the back, hips, or skull
  • bone weakness
  • plasmacytoma (a tumor made of plasma cells)
  • frequent fractures

Solitary plasmacytoma primarily develops in your:

  • ribs
  • vertebrae
  • femur
  • pelvis

Rarely, solitary plasmacytoma can occur in the skull, causing:

Learn more about the signs and symptoms of myeloma.

Multiple myeloma and solitary plasmacytoma develop when abnormal plasma cells replicate out of control.

Researchers don’t know why some people develop these conditions. It’s likely that a combination of genetic factors and environmental factors plays a role. Exposure to certain chemicals may increase your risk, but more research is needed to understand the connection.

Your doctor will start the diagnostic process by considering your family and personal medical history and performing a physical exam.

Multiple myeloma and other plasma cell conditions are usually confirmed with a bone marrow biopsy. Other tests that can support the diagnosis include:

  • blood tests
  • urine tests
  • imaging tests

Learn more about how multiple myeloma is diagnosed.

Treatment options for solitary plasmacytoma and myeloma include:

Your treatment team may also use a strategy of “watchful waiting” where they monitor the cancer before starting active treatment.

Learn more about myeloma treatment.

Risk factors for multiple myeloma include:

  • age: most cases are diagnosed in people over age 65
  • race: there’s a higher incidence of cases in African Americans than in Caucasian Americans
  • chemical exposure: exposure to radiation or chemicals such as benzene or some pesticides may increase your risk
  • family or medical history: a history of solitary plasmacytoma or MGUS will increase your risk
  • sex: people assigned male at birth

Solitary plasmacytoma generally occurs in middle-aged or older adults with an average age of 55 to 60. It occurs about twice as often in males.

Learn more about myeloma risk factors.

Myeloma isn’t usually considered curable because of relapses, even when treatment is effective. But treatments can help minimize your symptoms and prolong your life.

According to data from 2022 research:

  • about half of people with multiple myeloma live for at least 6 years
  • half of adults over the age of 75 live more than 5 years
  • half of people eligible for a bone marrow transplant live at least 8 years

In a 2020 study, researchers analyzed the survival rate of 59 people with solitary plasmacytoma from 2008 to 2017. The average survival time was 41 months.

Learn more about the outlook for people with multiple myeloma.

Here are some frequently asked questions people have about myeloma.

Is multiple myeloma common?

According to the American Cancer Society, the lifetime risk of developing multiple myeloma for someone living in the United States is about 1 in 132 (less than 1%). About 34,370 cases are diagnosed each year.

What’s the most common type of bone cancer?

The most common type of bone cancer is called osteosarcoma. It develops in early bone cells, most commonly in people ages 10 to 30.

Can I prevent multiple myeloma?

Right now, researchers aren’t sure exactly what causes myeloma, so there’s no known way to prevent it. An overall healthy lifestyle may help prevent cancer in general.

Multiple myeloma is a type of cancer that develops in plasma cells found in your bone marrow. Multiple myeloma and a related condition called solitary plasmacytoma can cause symptoms that affect your bones such as pain, weakness, and frequent fractures.

Some organizations consider multiple myeloma a bone cancer, while others do not.

Doctors use many different types of treatment to help manage your symptoms and improve your quality of life if you develop multiple myeloma. Your doctor can help you decide on the best treatment options for you.