Myeloma is a type of cancer that affects plasma cells. Plasma cells are part of the immune system, and they are responsible for making antibodies (also called immunoglobulins). Antibodies are immune proteins that help fight off infections.

Plasma cells and other blood cells are made in the bone marrow. If plasma cells develop a mutation (change) that makes them duplicate too fast, these abnormal plasma cells can begin to multiply uncontrollably, forming a tumor. These cancer cells may spread to other body parts. This process is called metastasis.

MyMyelomaTeam members have discussed their experiences with metastasis from myeloma. “In my case, myeloma spread through all the main bones,” one member wrote. “I had to have spinal surgery to prevent six vertebrae from collapsing.”

Keep reading to learn how myeloma metastasizes throughout your body and where it may spread.

Origin of Multiple Myeloma

A plasma cell tumor found in one localized region of the body is called a solitary plasmacytoma. If plasma cells cause a tumor in the bone, the tumor is called a solitary plasmacytoma of bone (SPB). SPB is often detected in the ribs, femur, spine, and pelvic bone.

Myeloma cells spread when they leave the bone marrow and travel through the bloodstream, just like normal cells.

“Solitary plasmacytoma” refers to a single tumor, while “multiple myeloma” means that there are multiple tumors, tumors in different body areas, or more than 10 percent of the bone marrow is made of abnormal plasma cells.

Read more about types of myeloma.

How Does Myeloma Spread Through the Body?

Cancerous cells leave the bone marrow through the bloodstream, just as normal immune cells leave the bone marrow to help fight infection. The cancerous cells can then travel throughout the body to form more tumors.

Common Sites for Multiple Myeloma Metastasis

Myelomas can be found in many bones, including the spine and ribs, where they can cause bone damage leading to fractures and abnormally high calcium levels. The most common sites of myelomas include the:

• Pelvis
• Spine
• Long bones (like the femur)
• Skull
• Ribs

Myeloma may spread and form tumors in other bones, in soft tissue next to bones, and in sinuses, lymph nodes, or organs including the lungs or liver.

Because the cancerous cells slowly destroy the bone, people with multiple myeloma typically complain of having bone pain, often in their back. This symptom can be easily overlooked, since back pain can be caused by many factors, most commonly strain from work or physical activity. People with back pain lasting longer than three weeks should see their doctor. However, metastatic myelomas are not limited to bones.

The Role of Extramedullary Disease in Metastasis

When myeloma cells spread, they can form a tumor in the soft tissues or organs of the body. Multiple extramedullary (outside the bone marrow) tumors occur when the cancer has metastasized. This condition is called extramedullary disease.

Extramedullary myeloma cells can develop:

• In soft tissues next to bone
• In the sinuses, nasal cavities, larynx, or the upper section of the throat
• In lymph nodes
• In an organ such as the lungs, liver, spleen, skin, or breasts

Extramedullary lesions can be found in people who have just been diagnosed with myeloma and in those who have had a myeloma relapse (a return of symptoms after a period of improvement). They’re most frequently found in the soft tissue next to the bones affected by myeloma. Less often, lesions are found in tissues or organs that aren’t near bones.

Incidence and Metastasis in Myeloma

Overall, myelomas are a fairly uncommon type of cancer. About 7.2 new myeloma cases per 100,000 people are diagnosed each year in the United States. Multiple myeloma is the most common type of plasma cell tumor, with a lifetime risk of less than 1 percent.

People may not notice symptoms of myeloma until after it’s spread.

SPB has a rate of 0.45 cases per 100,000 people in the United States. Extramedullary disease is rare, affecting about 7 percent to 15 percent of people newly diagnosed with myeloma. People who have relapsed from myeloma have a slightly increased risk of extramedullary disease, ranging from 6 percent to 20 percent.

SPB is more likely to metastasize to multiple myeloma than extramedullary plasmacytoma (EMP). SPB has a 50 percent progression rate, whereas 15 percent of EMP cases will progress to multiple myeloma. An older population-based study from the Netherlands found that 70 percent of people with SPB progressed to multiple myeloma.

Myeloma May Not Be Apparent Until Cancer Has Spread

It is difficult to detect myeloma early, before the disease has metastasized. That’s because many myeloma symptoms are also found in many other conditions. Symptoms of multiple myeloma may include back pain, nausea, loss of appetite, fatigue, constipation, and excessive thirst. Some people are asymptomatic and discover they have the disease during routine blood tests. Myeloma often causes abnormally high calcium levels in the blood, low red blood cell count or anemia, or high creatinine levels (when the kidneys are already involved). Because it can go unnoticed, the diagnosis of multiple myeloma typically doesn’t occur until the disease has spread.

Prognosis With Metastasized Myeloma

Although there is currently no cure for myeloma, survival rates continue to improve. New treatment options for cancer also continue to advance. Talk to your hematologist-oncologist (blood cancer specialist) or another doctor for information about which myeloma treatments may be right for you.

Talk With Others Who Understand

MyMyelomaTeam is the social network for people with myeloma and their loved ones. On MyMyelomaTeam, more than 27,000 members come together to ask questions, give advice, and share their stories with others who understand life with myeloma.

Has your multiple myeloma spread to soft tissues or bones? Did your oncology provider change your treatment options based on where myeloma spread? Share your experience in the comments below, or start a conversation by posting on your Activities page.