Smoldering myeloma, or smoldering multiple myeloma (SMM), is a rare pre-cancerous condition involving abnormal proteins and increased plasma cells in the bone marrow. It doesn’t have symptoms but can cause severe complications.
In some cases, SMM progresses to a rare blood cancer called multiple myeloma (MM). Anyone diagnosed with SMM should be evaluated for their risk of developing MM.
This article looks at possible signs, symptoms, and complications; the risk of the condition progression; and causes. It also discusses treatments and how to cope with the condition.
Symptoms, Signs, Complications
Smoldering myeloma is an asymptomatic condition. Often, people only realize they have SMM when a routine blood test comes back with signs of multiple myeloma, but they have no symptoms of the blood cancer, which include:
Why “Smoldering”?
SMM is called “smoldering” because it worsens slowly over time.
- Frequent infectionsBone painKidney problemsAnemia
Signs of SMM
The main sign of SMM is the presence of an M protein (myeloma protein) on routine lab tests.
The M protein is an abnormal antibody produced by malignant (cancerous) plasma cells.
Lab findings for SMM may include:
- M protein blood levels of 3 grams per deciliter (g/dL) or higher
- Plasma cells in the bone marrow that are 10% or higher
- A high urine level of Bence Jones protein (a protein made by plasma cells)
Complications of SMM
While it lacks earlier symptoms, over time, high levels of M protein in your blood can cause severe complications, such as:
Bone disorders: If SMM progresses to multiple myeloma, there is a significant risk of bone damage. About 85% of people with MM have a type of bone disorder such as osteolytic lesions or osteoporosis (bone loss). The spine, pelvis, and rib cage are the most common areas affected by MM-related disorders.
Kidney damage: Having too much M protein can overload the kidneys. The issue is further complicated by the excess calcium build-up that occurs in people with MM. The kidneys are then unable to properly filter waste. This can lead to kidney failure.
Nerve damage: Peripheral neuropathy, nerve damage that causes numbness or tingling in the feet or hands, is a common complication associated with M protein.
Compromised immune system: While this condition leads to high antibody levels, the antibodies produced don’t work right and overtake healthy cells. This leads to an impaired immune system and frequent infections.
Proper treatment can lower your chances of developing these complications.
Your Risk of Progression
While people with SMM are at risk of developing multiple myeloma, the risk drops over time:
- Within five years after diagnosis: 50% of cases will progress to MMBetween five and 10 years after diagnosis: Another 15% of cases will progress to MMAfter the 10-year mark: 1% of cases progress to MM per year
Determining your risk of multiple myeloma is important for treatment purposes. A 2017 study revealed evidence that early treatment of high-risk cases helped people live longer.
While treatment can lower your risk of progression, it can also cause severe side effects. So, only those at high risk should be treated.
To identify who’s most at-risk, healthcare providers rely on guidelines that look at three blood tests:
- M protein level in the blood = 2g/dL or higherBone marrow plasma cells = 20% or moreFree light chain (an immune system that protein that functions as an antibody) ratio = 20 or higher
This is sometimes called the 2/20/20 risk stratification or the 3 risk factor model.
Healthcare providers may also look for genetic abnormalities believed to play a role in MM. This is called the 4 risk factor model.
Under these models, your risk is determined by how many factors are positive. It determines your risk of progressing to multiple myeloma within two years.
If you’re in the high-risk category, you’re a candidate for immediate treatment aimed at slowing the progression of the disease and keeping you symptom-free.
Causes and Risk Factors
No one really knows what causes smoldering myeloma or multiple myeloma. Experts suspect several causal and risk factors are at play:
- Genetics: Specific gene mutations may cause high levels of plasma cells.
- Age: Diagnoses are most likely between the ages of 50 and 70.
- Race: Black people have double the rates of White people.
- Gender: Males have slightly higher rates than females.
Diagnosis and Monitoring
Most of the time, smoldering myeloma is diagnosed accidentally, when abnormal lab tests show up during a routine physical or when your healthcare provider is investigating a different problem.
Once you’re diagnosed with SMM, you will continue to be monitored to see if the disease is progressing to MM. It’s recommended that people with SMM be evaluated every 4 months, but those evaluations may be increased to 6-month intervals.
Diagnostic tests often used for ongoing observation of SMM may include:
- Blood tests: These measure M protein levels.
- Urine tests: 24-hour urine collections are standard upon diagnosis and again two to three months later.
- Bone marrow biopsy: This involves withdrawing cells with a needle and examining them for myeloma cells.
- Imaging tests (X-rays, PET scans, CT scans, or MRI): Upon diagnosis, these establish a baseline for your bones so your healthcare provider can spot abnormal changes down the road.
Treatment
Right now, multiple myeloma can’t be cured, so prevention is paramount. That’s why high-risk people with SMM should be treated.
Treatment typically involves:
- Chemotherapy drugs: Slow the progression from SMM to multiple myeloma. Examples are Revlimid (lenalidomide) and dexamethasone.
- Monoclonal antibodies: Newer drugs that help your immune system fight cancer. Examples are Darzalex (daratumumab), Sarclisa (isatuximab-irfc), and Empliciti (elotuzumab).
Ongoing research aims to determine what early treatments are most effective at preventing SMM progression.
Coping
Being diagnosed with smoldering myeloma can be emotionally challenging. It’s natural to fear that this pre-cancerous disorder will progress to cancer, especially if you’re at higher risk.
If you’re having trouble coping with your fears or suspect you’re clinically depressed, talk to your healthcare provider about mental health counseling.
It may also help to talk with friends and family or find a support group online or in your community.
Summary
SMM is a pre-cancerous condition that may progress to a blood cancer called multiple myeloma and cause serious health problems such as kidney damage, bone disorders, and an impaired immune system.
Healthcare providers asses your risk of SMM progressing to multiple myeloma based on the results of lab tests. People at high risk generally start treatment to prevent or delay multiple myeloma.
SMM appears to be caused by a mix of genetics, age, race, and gender. It’s diagnosed with blood, urine, and imaging tests plus a bone marrow biopsy. Treatment involves chemotherapy drugs or newer anti-cancer medication.
If you’re having trouble coping with your diagnosis, consider mental health counseling and/or a support group.
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By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer’s research.
