It’s a moment many of my patients describe with a bit of a jolt. You go in for a routine check-up, maybe some blood tests for something else entirely, and then you get a call. The tests picked up something… unusual. Sometimes, that “something” turns out to be what we call Smoldering Multiple Myeloma, or SMM. It sounds a bit scary, I know, and it’s perfectly normal to feel a wave of questions and concerns. The first thing to understand is that SMM isn’t active cancer, but it’s a heads-up that we need to keep a close eye on things.
Understanding Smoldering Multiple Myeloma (SMM)
So, what exactly is Smoldering Multiple Myeloma? Think of it like this: our bodies have these amazing cells called plasma cells. They’re a type of white blood cell, part of your immune system, and their job is to make antibodies to fight off infections. Now, in multiple myeloma (which is a type of blood cancer), these plasma cells start to change, becoming abnormal and multiplying out of control. They also start producing an abnormal protein, which we call an M protein.
Smoldering Multiple Myeloma is like an early stage before active multiple myeloma. Those abnormal plasma cells and M proteins are there, but they aren’t causing any of the serious problems in your body that we see with active myeloma – like bone damage or kidney trouble. It’s “smoldering,” meaning it’s there, but not yet a full-blown fire. For some folks, SMM might stay in this smoldering phase for years, and sometimes, it never develops into active multiple myeloma at all.
It’s worth mentioning another condition called Monoclonal Gammopathy of Undetermined Significance (MGUS). This is an even earlier stage where there are some abnormal plasma cells, but fewer than in SMM. Both MGUS and SMM are considered precursor conditions, meaning they could lead to multiple myeloma down the line.
How Common is SMM and Who Gets It?
SMM isn’t very common. Researchers think about 1 in every 100,000 people might develop it. To give you some perspective, active multiple myeloma affects about 7 in 100,000 people. It tends to show up more in folks who are a bit older, usually over 60. The average age when we diagnose it is somewhere between 62 and 67.
What’s the Risk of SMM Turning into Active Myeloma?
This is a big question, and understandably so. The risk isn’t the same for everyone, and it changes over time.
- In the first five years after an SMM diagnosis, about 10 out of 100 people each year might see it progress to active multiple myeloma.
- For the next five years (years 6-10), that risk drops to about 3 out of 100 people per year.
- And after 10 years, it’s down to about 1 out of 100 people per year.
Right now, we don’t have a crystal ball to say for sure who will progress. But there’s a lot of research looking into genetic changes that might help us predict this better in the future.
What Causes SMM, and Are There Symptoms?
Honestly, we don’t know the exact trigger that makes normal plasma cells go a bit haywire and lead to SMM. Researchers are looking into a few possibilities, like:
- Genetic mutations: Changes in certain genes (sometimes called oncogenes, which are involved in cell growth) might play a role.
- Obesity: Having a high level of body fat has also been looked at as a potential factor.
The tricky thing about SMM? It usually doesn’t cause any symptoms. Zero. Most people find out they have it, like I mentioned, through blood tests done for other reasons that happen to pick up those M proteins. Because it’s not actively causing damage yet, you wouldn’t typically feel any different.
How We Figure Out If It’s Smoldering Multiple Myeloma
If your initial tests show those M proteins, we’ll want to do a few more things to get a clearer picture and confirm if it’s SMM. These tests also give us a baseline, so we can track any changes over time. Here’s what we typically look at:
- Complete Blood Count (CBC): This checks your red cells, white cells, and platelets – all made in your bone marrow.
- Blood Chemistry Tests: We look at things like creatinine (to see how your kidneys are doing), albumin (another kidney and liver marker), and calcium levels (to check for any early bone issues).
- Quantitative Immunoglobulin Test: This measures the exact amount of those M proteins in your blood.
- Electrophoresis and Serum Immunofixation: Fancy names for tests that help us identify and characterize the M proteins.
- Urine Tests: You might be asked to collect your urine over a 24-hour period. We check this for M proteins too.
- Imaging Tests:
- X-rays: To look for any bone damage.
- Computed Tomography (CT) scan: Another way to get detailed images of your bones.
- Magnetic Resonance Imaging (MRI): This can be really good at spotting very early bone changes, especially in the spine.
- Bone Marrow Biopsy: This is a key test. A specialist (often a hematologist or oncologist) will take a small sample of your bone marrow, usually from the back of your hip bone. A pathologist (a doctor who examines tissues and cells) then looks at it under a microscope to see what percentage of the cells are plasma cells and if they’re abnormal. They might also do tests on the sample to look for specific DNA changes.
The “Rules” for Diagnosing SMM
For us doctors to say it’s SMM, certain things need to line up in your test results:
- Your blood test shows an M protein level greater than 3 grams per deciliter (g/dL).
- OR, your 24-hour urine test shows 500 milligrams or more of M protein.
- OR, a bone marrow biopsy shows that plasma cells make up between 10% and 59% of the cells in your bone marrow.
- AND critically, there’s no sign of the organ damage that active multiple myeloma can cause. This means no myeloma-related bone lesions (holes in the bones), your kidneys are working okay, your blood counts are normal, and your calcium levels are normal.
Managing Smoldering Multiple Myeloma: The “Watchful Waiting” Approach
So, if it’s SMM, what do we do? Right now, the standard approach is something called “watchful waiting.” This means we don’t usually jump in with treatment right away. Instead, we monitor you closely. You’ll have regular check-ups and tests to keep an eye on those M protein levels and the plasma cells in your bone marrow.
For some people who have a type of SMM that seems more likely to become active multiple myeloma (we call this “high-risk SMM”), your doctor might discuss starting treatment earlier. This is something that’s often explored in clinical trials, which are research studies looking for better ways to manage SMM and even prevent it from progressing. It’s a very individual decision, and your specialist is the best person to guide you.
It can feel a bit unsettling, this “waiting” part. I get it. It’s natural to want to do something. We’ll talk about what you can do in a moment.
What’s the Outlook?
This is unique to each person. Some people live with SMM for many, many years and never develop active multiple myeloma. Others might progress after some months or years. If you’re diagnosed with active multiple myeloma, there are many effective treatments available. Survival rates have been improving, with many people living well for five years or more after an active myeloma diagnosis. But remember, SMM isn’t active myeloma. Your doctor can give you the most personalized information about what to expect with SMM.
Unfortunately, there’s no known way to prevent SMM from developing in the first place.
Taking Care of Yourself with SMM
Even though we might be in a “watchful waiting” phase for Smoldering Multiple Myeloma, there’s still plenty you can do to support your overall health. It’s also a way to feel more in control, which I know can be really helpful when you’re feeling anxious about the unknown.
- Eat well: Focus on a balanced diet. If you’re not sure where to start, a chat with a nutritionist can be great.
- If you smoke, try to quit: It’s one of the best things you can do for your health, period.
- Get enough rest: Your body needs it.
- Protect yourself from infections: Simple things like washing your hands often can make a big difference. Ask us if you have specific concerns.
- Exercise regularly: Talk to us first, but gentle, regular exercise is usually a good thing.
- Look after your emotional well-being: It’s okay to feel worried or down. Talk to us, especially if these feelings stick around for more than a couple of weeks or get in the way of your daily life.
Key Things to Remember About Smoldering Multiple Myeloma
Living with an SMM diagnosis can bring up a lot of questions. It’s a journey, and we’re here with you. Here are the main takeaways:
- Smoldering Multiple Myeloma (SMM) is an early, asymptomatic condition where abnormal plasma cells are present but not yet causing active disease.
- It’s a precursor to active multiple myeloma, but not everyone with SMM will develop active cancer.
- Diagnosis involves blood tests, urine tests, imaging, and often a bone marrow biopsy.
- The main approach is “watchful waiting,” with regular monitoring.
- Lifestyle choices like a healthy diet and not smoking can support your overall well-being.
- Don’t hesitate to ask questions! We want to make sure you understand what’s happening.
You’re not alone in this. We’ll navigate this together, keeping a close watch and making sure you have all the information and support you need. We’ll discuss all options and what’s best for you every step of the way.