Multiple myeloma is a type of blood cancer affecting the plasma cells. MGUS, a noncancerous condition also affecting the plasma cells, can sometimes precede it.

Because multiple myeloma (MM) affects the production of healthy white blood cells, it affects the immune system. It can also affect other areas of the body, such as the bones, kidneys, and nerves.

Monoclonal gammopathy of unknown significance (MGUS) causes people to have abnormal antibodies in their blood. Despite this, they often appear otherwise healthy.

In a small number of people, MGUS progresses to MM.

Read more to learn about how MGUS becomes MM, as well as the symptoms, diagnosis, and outlook for people with these conditions.

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MGUS is a noncancerous condition affecting plasma cells. It sometimes precedes MM.

Usually, plasma cells in the bone marrow make antibodies. In people with MGUS, the plasma cells make many copies of abnormal proteins. These are called monoclonal proteins.

Unlike in MM, the plasma cells do not form a tumor or mass.

People with MGUS generally have no symptoms, although they sometimes have tingling or numbness in their hands or feet. Blood tests at routine checkups can lead to MGUS detection.

MM is a blood cancer that affects plasma cells.

Plasma cells play a significant role in the immune system. They make the antibodies that attack and kill disease-causing bacteria, viruses, or fungi.

If an individual has MM, abnormal plasma cells begin to grow excessively. They overtake the production of healthy cells.

These cancerous plasma cells make abnormal monoclonal proteins. These harm the body.

Learn more about MM.

In some cases, MGUS can become MM. People with MGUS have a 1% risk for the condition progressing to MM each year.

A doctor can usually estimate the individual’s risk for progressing by testing their blood for specific markers. Conducting a risk assessment helps doctors understand how much monitoring and care a person needs.

The type of MGUS a person has affects their risk assessments. One 2019 study showed people with low- and intermediate-risk MGUS can progress to high-risk MGUS in 5 years.

Usually, only people with intermediate- and high-risk MGUS have annual follow-up tests to check for disease progression. The study indicates people with low-risk MGUS may benefit from more frequent testing.

Learn more about MGUS blood tests.

People with MGUS often have no symptoms.

They may start to show symptoms if the disease progresses to MM. Symptoms of MM include:

  • infection
  • weight loss
  • muscle weakness and numbness
  • confusion
  • fatigue
  • digestive issues
  • osteoporosis and broken bones
  • shortness of breath
  • dizziness
  • constipation

Learn more about symptoms of MM.

There are several tests used to diagnose MGUS and MM.

MGUS

Because people with MGUS often have no symptoms, doctors may diagnose the condition when a routine blood test finds high protein levels in the blood.

Further testing can then determine if the protein is a monoclonal protein. These are the abnormal proteins created by plasma cells, and their presence indicates MGUS.

Multiple myeloma

A variety of tests can diagnose MM, including:

  • blood counts
  • blood chemistry tests
  • quantitative immunoglobulins
  • beta-2 microglobulin
  • electrophoresis
  • urine tests
  • serum-free light chains
  • core needle biopsy
  • fine-needle aspiration biopsy
  • bone marrow biopsy
  • imaging tests including PET scans, CT scans, bone X-rays, and MRI scans

Doctors will also consider the person’s symptoms and medical history, and may perform a physical exam.

Learn more about how doctors diagnose MM.

MGUS becomes more common as people age. According to a 2014 study, about 2% of people over 50 years old have the condition.

Certain conditions can increase an individual’s risk for MGUS. These include:

  • being older
  • being male
  • being Black
  • having family history of MGUS

Some additional risk factors that may be associated with MGUS include inflammatory disorders, smoking, and several specific past infections.

Additionally, it is important to note that MGUS has the same risk factors as MM. Additional risk factors of MM include having obesity and other plasma cell diseases such as MGUS or solitary plasmacytoma.

MGUS has no effect on most people, and they are unlikely to have any symptoms.

People with MGUS have a 1% chance of developing MM, lymphoma, or amyloidosis each year. The likelihood of progressing to one of these diseases increases as their monoclonal protein levels increase.

For individuals with MM, the outlook is variable. Factors that affect this include a person’s age, disease classification, and stage. According to statistics from 2010 to 2016, the 5-year survival rate of those with MM is 53.9%.

MM treatment aims to remove or destroy cancer cells.

Doctors may be unable to cure some individuals fully. Instead, they may need to administer regular chemotherapy or radiation therapy to keep cancer cells at bay. Follow-up appointments are crucial.

Additionally, people recovering from MM may be at risk for relapsing, developing other types of cancer, or both.

A 2019 study analyzed 511 MM survivors for 12 months following the start of their treatment. The researchers noted that 16% of the study participants experienced early relapse, and the median amount of time spent in remission before relapse was 8 months.

MGUS is a noncancerous condition characterized by abnormal plasma cells. It is more common in older adults and may precede MM.

People are often diagnosed with MGUS during a routine blood test. When they are diagnosed with MGUS, doctors assign a risk level of progression, which determines their level of follow-up care.

This care aims to help prevent or anticipate MGUS progressing into MM. This is a type of cancer affecting the plasma cells. People with MM should have annual follow-up appointments to check for relapse and any side effects of their treatment.