Treatments for smouldering multiple myeloma

Smouldering multiple myeloma is a condition that is between a precancerous condition called monoclonal gammopathy of undetermined significance (MGUS) and active (or symptomatic) multiple myeloma. Smouldering multiple myeloma does not cause any symptoms (called asymptomatic) and is usually found during routine blood tests.

Smouldering multiple myeloma has all of the following features:

• There are no myeloma defining events (MDEs).
• Myeloma cells make up 10% to 60% of the blood cells in the bone marrow.
• The M-protein level in the blood is 30 g/L or more, or the M-protein level in the urine is 500 mg or more over a 24-hour period.

There is about a 10% risk that smouldering multiple myeloma will progress to active multiple myeloma in the first 5 years after a diagnosis. In the 5 years after that, there is about a 3% risk that it will progress. And in the years after that, there is about a 1.5% risk.

Doctors try to predict when people with smouldering multiple myeloma will develop active multiple myeloma. Smouldering multiple myeloma can be low risk or high risk.

Low-risk smouldering multiple myeloma has both of these features:

• Myeloma cells make up less than 10% of the blood cells in the bone marrow.
• The M-protein level in the blood is 30 g/L or more.

High-risk smouldering multiple myeloma has any 2 or 3 of the following features:

• Myeloma cells make up more than 20% of the blood cells in the bone marrow.
• The serum free light chain ratio is greater than 20.
• The M-protein level in the blood is 30 g/L or more.

Other high-risk characteristics include the following:

• There is an increase of M-protein levels in the blood by 25% or more in 2 successive evaluations within 6 months.
• Myeloma cells make up more than 50% to 60% of the blood cells in the bone marrow.
• There are genetic characteristics, such as t(4;14), del17p or 1q gain.
• The number of myeloma cells in the blood has increased.
• An MRI shows many bone abnormalities or one lesion.
• A PET-CT scan shows a lesion in the bone but without osteolytic bone destruction.

On average, high-risk smouldering multiple myeloma progresses to active multiple myeloma about 2 years after their diagnosis.

Treatment decisions are based on whether you have low-risk smouldering multiple myeloma or high-risk smouldering multiple myeloma. What you want is also important.

The standard treatment for low-risk smouldering multiple myeloma is watchful waiting. Watchful waiting means that your healthcare team watches the cancer closely rather than giving other treatment right away.

You will have blood tests every 3 to 4 months for a year. If the disease is stable, blood tests will be done every 6 months for life or until there are signs of the disease getting worse (called disease progression).

If you have bone loss, you will be given a bisphosphonate once a year to slow down further bone loss.

Other treatments may be started if there is an increase in M-protein levels and a decrease in hemoglobin levels in the blood over 12 months.

Find out more about watchful waiting for multiple myeloma and supportive therapy for multiple myeloma.

The standard treatment for high-risk smouldering multiple myeloma is watchful waiting. Watchful waiting means that your healthcare team watches the cancer closely rather than giving other treatment right away.

You will have blood tests every 2 to 3 months for the first year. If the disease is stable, you will have blood tests every 4 to 6 months for 5 years or until there are signs the disease is getting worse.

If you have bone loss, you will be given a bisphosphonate once a year to slow down further bone loss.

You may also be asked to participate in a clinical trial for high-risk smouldering multiple myeloma. Clinical trials look at new ways to prevent, find and treat cancer.

Find out more about targeted therapy for multiple myeloma, supportive therapy for multiple myeloma and clinical trials.