Smouldering myeloma

Smouldering myeloma is an early form (‘precursor’) of myeloma. It is considered as the second stage of a disease spectrum which starts as monoclonal gammopathy of undetermined significance (MGUS), and may progress to become active myeloma, but usually at a slow rate. 

We have outlined some key information about smouldering myeloma on this webpage. Read more about smouldering myeloma in our Smouldering myeloma infosheet.

Plasma cells, immunoglobulins  and smouldering myeloma

Plasma cells are found in bone marrow (the spongy centre of our bones) where they form part of our immune systems. Healthy plasma cells make antibodies (which are also called immunoglobulins), to help fight infection.  

In smouldering myeloma, some of these plasma cells become abnormal because of DNA changes. Instead of making helpful immunoglobulins to fight infection, the abnormal plasma cells make and release an abnormal type of immunoglobulin, called paraprotein.  

This paraprotein doesn’t have any useful function in your body, and can become harmful at higher levels. Because there is only a small amount of paraprotein in your body, it usually doesn’t cause any problems. 

Read more about paraprotein, in our Understanding paraprotein in myeloma infosheet.

In smouldering myeloma, abnormal plasma cells begin to build up in the bone marrow but do not cause any damage to the body.  

Most of the time, smouldering myeloma doesn’t cause symptoms, which is why it’s sometimes called ‘asymptomatic’ and why many people don’t realise they have it. You may only find out you have smouldering myeloma by chance when you’re having blood tests done for another reason. 

What causes smouldering myeloma?

The cause of smouldering myeloma is not yet known, although researchers believe that there are genetic and environmental factors involved.  

We do know that some factors increase the risk of developing smouldering myeloma: 

• Age: As we get older, our cells make more mistakes when making new cells and our immune system is less able to detect these abnormal cells.  
• Ethnicity: Smouldering myeloma is more common in people of Black ethnicity. 
• Family history: If a close relative has MGUS, smouldering myeloma, or active myeloma, you have a slightly higher chance of developing smouldering myeloma.  
• Having a health condition that affects the immune system or certain viruses, such as HIV, hepatitis or herpes. 
• Exposure to certain chemicals or radiation, including agricultural chemicals, benzene, and solvents. 

I don’t think anybody wants to hear they have a serious health condition, especially out of the blue, and one they have never heard of before. But, with the support and information from my health professionals about what the future could look like, I have accepted it as part of what life throws at us. Worrying about it does not change anything. I try not to worry and I work on improving my overall wellbeing.

– Nigel, Victoria

How is smouldering myeloma diagnosed?

As smouldering myeloma doesn’t cause any symptoms, it is usually diagnosed when paraprotein is found by chance when you’re having a routine check-up or tests for other health conditions.  

If you have been diagnosed with MGUS, your treating team may find it has progressed to smouldering myeloma when doing your regular MGUS monitoring tests, or because you develop symptoms and your team then does further tests.   

Once the paraprotein has been found, your doctor will need to do some more tests to confirm that you have smouldering myeloma.  

These further tests are usually ordered by a haematologist and include:  

• Blood tests
• Urine (wee) tests
• Imaging tests
• Bone marrow aspiration and trephine (BMAT) biopsy

Read more about these tests on our Understanding your tests webpage.

How is smouldering myeloma managed?

Most people with smouldering myeloma don’t benefit from treatment because the condition isn’t causing any harm to their body. Instead, regular monitoring is essential to make sure progression to active myeloma is picked up early.  

Monitoring usually involves blood and urine tests to track your level of paraprotein or free light chains. Your haematologist will let you know how often you need these tests. 

If you’re at high risk of progression, you may be offered a clinical trial for early treatment. Ask your haematologist about trials that might be available to you. 

Normally, treatment will begin when your smouldering myeloma is developing into active myeloma. The timing of starting treatment will depend on your individual test results, symptoms, general health and other individual factors, which you and your haematologist will discuss together.  

Progression from smouldering myeloma to active myeloma

Smouldering myeloma is part of a disease spectrum: 

• All cases of smouldering myeloma start as monoclonal gammopathy of undetermined significance (MGUS), a non-cancerous condition where small numbers of damaged plasma cells in the bone marrow produce a paraprotein that can be detected in your blood. Everyone with smouldering myeloma first had MGUS (even if you weren’t aware of it) although, not all people with MGUS will develop smouldering myeloma.The reason people develop MGUS remains unknown. 
• When the damaged plasma cells start to produce a higher level of paraprotein and/or build up at higher levels in the bone marrow, but cause no symptoms or harm to the body, MGUS has progressed to smouldering myeloma. 
• Some people with smouldering myeloma will eventually progress to active myeloma. When paraprotein levels and plasma cell numbers rise, start to cause symptoms or damage to the body, smouldering myeloma has progressed to active myeloma and needs treatment.  

The image below gives a visual guide to the differences between MGUS, smouldering myeloma, and active myeloma.  

I was having regular blood tests for MGUS, and when my paraprotein numbers started climbing more rapidly, the blood tests got closer together. I then had a bone marrow biopsy and more tests, and was told I now had smouldering myeloma, but still did not need treatment.

– Simon, Tasmania

When will my myeloma become active?

Low-, intermediate- and high-risk smouldering myeloma

Once your haematologist has confirmed that you have smouldering myeloma, they will then work out your risk of progressing to active myeloma. 

While we can’t pinpoint exactly when your smouldering myeloma will start progressing, there are some factors that help us understand your risk of progressing sooner rather than later. 

These include: 

• paraprotein level higher than 20g/L 
• free light-chain ratio higher than 20 
• more than 20% abnormal plasma cells in your bone marrow. 

The number of risk factors you have will be used to work out if you are at low, intermediate or high risk of progressing to active myeloma within 2 years.

Number of risk factors	Risk group	Risk of progression to active myeloma over 2 years
0-1	low-risk	6.2%
1	intermediate-risk	17.9%
2-3	high-risk	44.2%

FISH test

Your haematologist may also order a type of genetic test called fluorescent in situ hybridisation (FISH) to look for DNA abnormalities. This test is done using the sample taken when you had a bone marrow biopsy. 

The results of your FISH test may be combined with your risk score from the table to give more information about your possible rate of progression to active myeloma. You can read more about the FISH test in our Understanding bone marrow tests in myeloma infosheet.

Your haematologist will use all these test results to decide how often you will need monitoring so that progression to active myeloma can be picked up as soon as possible. 

Your risk of progressing to active myeloma is lower if you have had smouldering myeloma for a long time without signs of progression.

To learn more about FISH and other bone marrow tests see our infosheet Understanding bone marrow tests in myeloma

When I was diagnosed with SMM, my doctor told me that I had some high-risk features. She explained that this meant I had a high chance of progressing to active myeloma sooner rather than later. At first, I felt very anxious about this, but now I have more understanding and am confident about the plan my doctor and I have in place for monitoring — and for when I need to start treatment. I also found speaking to a psychologist and others living with SMM helped me cope with my anxiety.

– Fatima, Northern Territory

What are the signs that my smouldering myeloma might be progressing? 

Let your haematologist know as soon as you notice any symptoms that are new or getting worse – don’t wait for your next blood test or appointment.  

Contact your haematologist if you notice:  

• an unexpected broken bone (from only a small or unknown injury) 
• unexplained pain, especially in your back or ribs  
• unexplained bruising or bleeding  
• feeling tired, light-headed or breathless  
• tingling or numbness in your hands or feet 
• losing weight without trying  
• frequent infections or infections that don’t get better easily 
• feeling less healthy overall.  

In your blood or urine tests, your doctor will be looking for: 

• increased calcium levels  
• reduced kidney function  
• anaemia (low red blood cells) 
• increasing paraprotein or light chain levels. 

Living well with smouldering myeloma

Being diagnosed with smouldering myeloma is understandably a challenging and unsettling time that can create anxiety about the future for you and your family.

It can be especially challenging to be told you have a health condition that is likely to progress, but for which treatment is not yet recommended. People with smouldering myeloma tell us that they are often most anxious when they are first diagnosed and then each time as they are waiting for the results of their monitoring tests. 

Additionally, you and your family and friends may not have heard of smouldering myeloma before your diagnosis, and this can make living with the condition feel quite isolating at times. 

While it’s natural to be concerned, there are ways to help you manage these feelings, while staying positive and proactive. 

Here are some ideas for finding support, dealing with uncertainty, and staying positive: 

• Talk to someone: Share your feelings with a trusted friend, family member, or your treating team. See the last page of this infosheet for Myeloma Australia support services. 
• Living with uncertainty: Even though your anxiety may be worse when your monitoring tests and results are due, you can feel reassured that these tests mean that any changes will be found early, helping your treating team to take any action as soon as needed. Keep up-to-date with your monitoring tests and appointments, and let your haematologist know about any new symptoms so they can be checked. Keep in mind that new symptoms may not be related to myeloma.
•  Take it one step at a time: While it’s normal to have bad days, try not to let the ‘what ifs’ and worry take over. Do your best to stay present and focus on the people and activities that bring you joy. – Many people find that relaxation, mediation and mindfulness practices can help them to live better with uncertainty. 
• Focus on what you can control: Living a healthy lifestyle — like eating well, staying active, and prioritising your sleep — can boost both your physical and mental wellbeing. If you ever feel anxious or overwhelmed, don’t hesitate to reach out to your treating team or our Specialist Myeloma Nurses for support. They’re here to help you every step of the way.

Having the support of Myeloma Australia and the information available on their website, along with knowledge of the work that Myeloma Australia is doing in the background, is a great comfort. Myeloma Australia is my go-to place for the current state of play for treatments, information, and a way of connecting with others affected by myeloma. I’m a regular attendee to the VIC Statewide Cuppa and Catch Up and Smouldering Myeloma Support Group (via Teams meetings). There are lots of positive people and good advice in these groups.

– Nigel, Victoria