Multiple Myeloma: Definition, Symptoms, and Risk Factors

Dr. Michael Styler has specialized experience treating multiple myeloma, and offers the latest treatment options to patients at Fox Chase.
Dr. Michael Styler has specialized experience treating multiple myeloma, and offers the latest treatment options to patients at Fox Chase.

What is Multiple Myeloma?

Multiple myeloma is a cancer of white blood cells called plasma cells, which are found primarily in the bone marrow (the soft tissue in the center of the bone). Bone marrow is where red blood cells, white blood cells, and platelets are produced, and they all perform different functions that are critical to keeping the body healthy. Normal plasma cells that are produced there are an important part of the immune system, making antibodies that attack and kill germs.

Multiple myeloma occurs when plasma cells keep reproducing instead of dying when they become old or damaged. This abnormal genetic change turns plasma cells into myeloma cells. Rather than making protective antibodies, the myeloma cells produce an abnormal M-protein that has no power to clear infection.

As they continue to make millions of copies of themselves, a group of myeloma cells forms. This crowds out healthy blood cells, frequently destroying bone tissue and spreading throughout the body.

Multiple Myeloma Symptoms

Sometimes, multiple myeloma does not cause symptoms. The disease may be discovered through routine bloodwork or when a test is done for another condition and a level of protein is found that is higher than normal.

The following list includes signs of multiple myeloma that may prompt you to see your physician, although they could indicate many other conditions as well:

  • Bone pain, especially in the spine or ribs
  • Unexplained kidney failure or frequent infections
  • Weakness of the arms or legs
  • Extreme fatigue
  • Bruising or bleeding easily
  • Frequent fevers
  • Breathing problems

Risk Factors: What Causes Multiple Myeloma?

Like other types of cancer, researchers haven’t yet identified the exact reason why multiple myeloma occurs. The most significant risk factor for the disease is advanced age, and most people are at least 65 years old when they are diagnosed.

Other risk factors for multiple myeloma include:

  • Gender: Men are more likely to develop the disease than women.
  • Race: Black individuals are approximately twice as likely to be diagnosed with the condition than white individuals.
  • Family history: The chance of developing multiple myeloma increases if a parent or sibling has been diagnosed with it.
  • Obesity: Being overweight or obese increases the risk of multiple myeloma.

Having any of these risk factors does not mean you will develop multiple myeloma, and many people with this condition have no risk factors.

Indolent and Smoldering Myeloma

Some cases of multiple myeloma grow slowly and are asymptomatic. These cases are called indolent or smoldering myeloma. Patients with these conditions tend to be closely monitored rather than treated immediately.

Other Plasma Cell Disorders

Along with multiple myeloma, there are numerous types of plasma cell dyscrasias (disorders), which are characterized by production of an abnormal protein.

MGUS (Monoclonal Gammopathy with Undetermined Significance)

This condition represents two-thirds of all plasma cell disorders. Doctors see evidence of abnormal protein but no other evidence of myeloma. The incidence increases with age and occurs in up to 5.3 percent of people age 70 and older. Treatment is only indicated if this condition progresses to multiple myeloma.


Amyloidosis is closely related to multiple myeloma. It can be its own disease or a component of some forms of multiple myeloma. This condition occurs when an abnormal protein (called amyloid) builds up in the organs and interferes with their normal function.

Light-Chain Amyloidosis

The most common type of amyloidosis, light-chain amyloidosis usually affects the heart, kidneys, liver, and nerves. Sometimes, when the body produces light chains, the protein forms an unusual matrix that sticks together in an odd way and gets deposited into unique places. These deposits of abnormal protein can cause organ failure.

Waldenström Macroglobulinemia (WM)

The cells in people with WM are similar to those seen in both multiple myeloma and non-Hodgkin lymphoma.

Extramedullary Plasmacytoma

This condition involves a single clump of myeloma cells outside the bone marrow. Plasmacytomas can form in the skin, muscle, lungs, or almost any other part of the body.