Smoldering Multiple Myeloma (SMM)

Smoldering multiple myeloma (SMM) is a precursor or early sign that someone may develop multiple myeloma (MM), a rare blood cancer that happens when certain white blood cells mutate into abnormal cells. SMM may take years to become MM, and in some cases, people who have smoldering multiple myeloma never develop multiple myeloma.


What is smoldering multiple myeloma?

Smoldering multiple myeloma (SMM) is a blood and bone marrow disorder that can become the rare blood cancer active multiple myeloma. Multiple myeloma (MM) happens when specialized white blood cells in your immune system mutate into abnormal cells. Smoldering multiple myeloma may take years to become active multiple myeloma. In some cases, people who have this condition never develop active MM. Healthcare providers manage SMM by monitoring for signs it’s becoming active multiple myeloma. Healthcare providers may recommend clinical trials that evaluate better ways to manage smoldering multiple myeloma and prevent it from becoming active multiple myeloma.

Is smoldering multiple myeloma cancer?

Even though smoldering multiple myeloma isn’t treated as a cancer, it may develop into active multiple myeloma, which is cancer that can be treated. Just as unusual spots or moles on your skin may be an early sign of skin cancer, SMM means you could develop MM. That’s why healthcare providers closely monitor people with this disorder.

What other conditions are precursors for multiple myeloma?

Monoclonal gammopathy of undetermined significance (MGUS) is another disorder that may develop into active multiple myeloma. Like SMM, healthcare providers consider MGUS (pronounced “EM-gus”) a precursor to multiple myeloma.


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How does smoldering multiple myeloma affect my body?

If you have this disorder, you don’t have symptoms that affect your body. Many times, people learn they have SMM after routine tests done for other reasons. Those blood tests may show you have abnormal plasma cells producing M proteins.

Blood tests will show evidence that the abnormal plasma cells are producing abnormal immune proteins (M proteins), and if a bone marrow biopsy is performed, healthcare providers would expect to see these abnormal plasma cells in the marrow. However, in the smoldering state, myeloma isn’t causing problems in your body, so people with SMM typically don’t have any symptoms.

Who may develop smoldering multiple myeloma?

This disorder typically affects people over age 60. The median age of diagnosis is between 62 and 67.


Is smoldering multiple myeloma a common disease?

No, it’s not. Researchers estimate that 1 in 100,000 people develop the disorder. In contrast, multiple myeloma affects 7 in 100,000 people.

What is the risk of smoldering multiple myeloma becoming active multiple myeloma?

Each year during the first five years after diagnosis, 10% of people who have SMM may develop active MM. That percentage drops to 3% per year for the next five years, and to 1% per year after the first 10 years.

Can tests predict if someone will develop multiple myeloma?

Right now, there aren’t tests that predict if someone will develop multiple myeloma. Healthcare providers are evaluating whether analyzing genetic changes linked to MM may help identify if someone who has SMM will develop MM.

Symptoms and Causes

What causes smoldering multiple myeloma?

Researchers know abnormal plasma cells and proteins are signs of smoldering multiple myeloma (SMM) and multiple myeloma (MM). They aren’t sure what triggers the change that turns normal plasma cells into abnormal cells. They’re exploring some potential causes:

  • Genetic mutations: Researchers are investigating links between mutating or changing oncogenes (cells that promote growth) and multiple myeloma and smoldering multiple myeloma.
  • Having obesity: This is having high levels of body fat.


What are the symptoms of smoldering multiple myeloma?

SMM doesn’t cause any noticeable symptoms.

Diagnosis and Tests

How do healthcare providers diagnose smoldering multiple myeloma?

Healthcare providers may do several tests to confirm you have this disorder. Remember, routine tests that show signs of M protein in blood and/or pee (urine) may be the first indication of smoldering multiple myeloma. Healthcare providers may do other baseline tests so they can track changes that may indicate you’re developing multiple myeloma. Those tests include:

  • Complete blood count (CBC): This test measures your red and white blood cell numbers and platelet counts that your bone marrow produces.
  • Blood chemistry test: This test shows your creatinine levels (how well your kidneys work), albumin levels (how well your kidneys and liver function) and calcium levels (to check for bone breakdown).
  • Quantitative immunoglobulin test: This blood test measures the levels of M proteins (immune proteins) in your blood.
  • Electrophoresis and serum immunofixation: These tests look for M proteins (immune proteins) in your blood.
  • Urine tests: Healthcare providers may ask you to collect your pee (urine) at home over a 24-hour period so they can test for M proteins (immune proteins) in your pee.
  • X-rays: Healthcare providers use X-rays to look for bones damaged by multiple myeloma.
  • Computed tomography (CT) scan: This is another way to look for bone damage.
  • Magnetic resonance imaging (MRI): This test uses radio waves and strong magnets to create detailed images of your bones and spine. Healthcare providers may use this test to look for evidence of early bone damage.
  • Bone marrow biopsies: Healthcare providers may do bone marrow biopsies to analyze the percentage of normal and abnormal plasma cells in your bone marrow. They may also test your bone marrow sample for changes in your DNA that may drive cancer growth.

What are the criteria for smoldering multiple myeloma?

When healthcare providers talk about criteria, they’re talking about test results that meet medical standards for making a certain diagnosis. The criteria for SMM are:

  • A blood test shows an M protein > 3g/dl (3 grams per deciliter of blood.)
  • A 24-hour urine tests show 500 or more milligrams of protein OR...
  • Bone marrow biopsy shows that plasma cells make up between 10% and 59% of blood cells in your bone marrow, AND...
  • There’s no sign of abnormal bone lesions or kidney damage that myeloma may cause, your blood counts are normal and your calcium levels are normal.

Management and Treatment

How do healthcare providers treat this disorder?

“Watchful waiting” is the current standard of care for smoldering multiple myeloma. In watchful waiting, healthcare providers do regular tests to monitor M protein levels and levels of plasma cells in your bone marrow.

Some people have a form of the disorder that’s considered likely to develop into active multiple myeloma. In that situation, some healthcare providers may recommend starting MM treatment earlier. If you have SMM, your provider is your best resource for information and treatment recommendations.


Can I reduce my risk for developing smoldering multiple myeloma?

No, there’s no known way to prevent SMM.

Outlook / Prognosis

How long can you live with smoldering multiple myeloma?

This disorder affects people in different ways. Some people may have it and never develop multiple myeloma. Some people are diagnosed with the disorder but only develop MM months and years after they’re diagnosed. If you’re concerned about living with SMM, ask your healthcare provider what you might expect. They’re your best resource for specific information.

How long can you live with multiple myeloma?

Approximately 40% to 82% of people with multiple myeloma are alive five years after diagnosis.

Living With

How do I take care of myself?

If you have smoldering multiple myeloma, you may not need treatment right away — or ever. Your healthcare provider will recommend that you have regular checkups and tests so they can look for signs that your condition has changed to multiple myeloma. If you’re living with SMM, you may feel anxious and irritable because you want to take action and do something about your illness. Here are some steps you can take to support your overall health:

  • Eat well-balanced meals. If you need suggestions, talk to a nutritionist for ideas on healthy eating.
  • If you smoke, please try to stop.
  • Get enough rest.
  • Protect yourself from infection. Ask your provider for ways to prevent infection.
  • Exercise regularly, but talk to your provider first so you don’t overdo it.
  • Pay attention to your emotional health. If you feel depressed about your situation talk to your provider, especially if sadness and depression last for more than two weeks or interfere with your daily activities.

What questions should I ask my healthcare provider?

If you have smoldering multiple myeloma, here are some questions you may want to ask:

  • Why did I develop this disorder?
  • How will it affect my daily life?
  • How long will it take to develop multiple myeloma?
  • Should I watch for certain symptoms that may indicate I have multiple myeloma?
  • Is there treatment to prevent SMM from becoming multiple myeloma?

A note from Cleveland Clinic

Smoldering multiple myeloma (SMM) is a precursor to multiple myeloma (MM). But not everyone who has SMM develops active multiple myeloma. Understandably, people who have SMM want to know if they’ll develop active multiple myeloma, and if they will, when. These are tough questions. Healthcare providers don’t have all the answers right now. Recent research shows mapping changes in certain genes may make it easier to estimate if and/or when smoldering multiple myeloma may become MM. If you have this disorder, ask your healthcare provider if there’s new information that applies to your situation. They’ll be happy to help.

Medically Reviewed

Last reviewed on 07/13/2022.

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