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.
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.
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.
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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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.
This disorder typically affects people over age 60. The median age of diagnosis is between 62 and 67.
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.
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.
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.
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:
SMM doesn’t cause any noticeable symptoms.
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:
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:
“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.
No, there’s no known way to prevent SMM.
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.
Approximately 40% to 82% of people with multiple myeloma are alive five years after diagnosis.
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:
If you have smoldering multiple myeloma, here are some questions you may want to ask:
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.
Last reviewed by a Cleveland Clinic medical professional on 07/13/2022.
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