What is the Difference Between Smoldering Myeloma and Multiple Myeloma?

Smoldering multiple myeloma (SMM) and multiple myeloma (MM) are both conditions related to the development of abnormal plasma cells in the blood and bone marrow. However, there are key differences between the two:

Symptoms: SMM is asymptomatic, meaning it does not cause any noticeable symptoms. In contrast, MM is an active blood cancer that can cause organ damage, such as bone fractures, kidney failure, and anemia.
Disease stage: SMM is considered a precursor or early stage of MM. It is an intermediate stage between monoclonal gammopathy of undetermined significance (MGUS) and active MM.
Risk of progression: The risk of SMM progressing to MM is higher than the risk of MGUS progressing to MM. In the first 5 years after diagnosis, 10% of SMM patients per year may develop MM, compared to only 1% of MGUS patients per year.
Treatment: SMM is typically not treated as a cancer, but rather managed by monitoring for signs of progression to active MM. MM, on the other hand, is treated as a cancer with various therapies, including chemotherapy, targeted therapy, and stem cell transplantation.
Prognosis: SMM may not necessarily progress to MM. Some patients with SMM may never develop MM. In contrast, MM is a more advanced stage of the disease with its own set of complications and treatments.
Monitoring: The standard of care for SMM is to "watch and wait," with regular monitoring by healthcare providers for signs of progression to active MM. In some cases, patients with SMM may be eligible for clinical trials that evaluate better ways to manage the condition.

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Comparative Table: Smoldering Myeloma vs Multiple Myeloma

Smoldering multiple myeloma (SMM) and multiple myeloma (MM) are both clonal plasma cell disorders, but they differ in their clinical presentation and risk of progression. Here is a table summarizing the differences between the two:

Feature	Smoldering Multiple Myeloma (SMM)	Multiple Myeloma (MM)
Definition	Asymptomatic clonal plasma cell disorder with a higher risk of progression to MM compared to monoclonal gammopathy of undetermined significance (MGUS)	Symptomatic clonal plasma cell disorder characterized by myeloma-defining events
Risk of Progression	10% per year for the first 5 years after diagnosis, then reducing to 3% per year over the next 5 years, and 1.5% per year thereafter	Progression to MM occurs at a higher rate than SMM
Prevalence	0.5% in persons over 40 years old, higher in men than women, and increases with age	Present in approximately 5% of the population above the age of 50
Diagnosis	Defined by a 10% to 60% plasma cell infiltration in the bone marrow and/or monoclonal (M) protein in the absence of myeloma-defining events	Diagnosed when myeloma-defining events are present
Treatment	Close monitoring for progression is the best management for most patients with SMM	Treatment options vary depending on the patient's condition and response to therapy

It is important to differentiate SMM from MGUS because the risk of progression to MM is higher in SMM. While close monitoring for progression remains the best management for most patients with SMM, ongoing trials of innovative treatment combinations and novel therapeutic approaches are expected to improve the understanding and management of SMM.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.