No one knows the exact causes of multiple myeloma. Doctors seldom know why one person
develops this disease and another doesn't. However, we do know that multiple myeloma isn't contagious. You cannot catch it from another person.

Research has shown that certain risk factors increase the chance that a person will develop this disease. Studies have found the following risk factors for multiple myeloma:

• Age over 65: Growing older increases the chance of developing multiple myeloma. Most people with myeloma are diagnosed after age 65. This disease is rare in people younger than 35.
  
  
• Race: The risk of multiple myeloma is highest among African Americans and lowest among Asian Americans. The reason for the difference between racial groups is not known.
  
  
• Being a man: Each year in the United States, about 11,200 men and 8,700 women are diagnosed with multiple myeloma. It is not known why more men are diagnosed with the disease.
  
  
• Personal history of monoclonal gammopathy of undetermined significance (MGUS): MGUS is a benign condition in which abnormal plasma cells make M proteins. Usually, there are no symptoms, and the abnormal level of M protein is found with a blood test. Sometimes, people with MGUS develop certain cancers, such as multiple myeloma. There is no treatment, but people with MGUS get regular lab tests (every 1 or 2 years) to check for a further increase in the level of M protein. They also get regular exams to check for the development of symptoms.
  
  
• Family history of multiple myeloma: Studies have found that a person's risk of multiple myeloma may be higher if a close relative had the disease.

Many other suspected risk factors are under study. Researchers have studied whether being exposed to certain chemicals or germs (especially viruses), having alterations in certain genes, eating certain foods, or being obese increases the risk of developing multiple myeloma. Researchers continue to study these and other possible risk factors.

Having one or more risk factors does not mean that a person will develop myeloma. Most people who have risk factors never develop cancer.

Dictionary Terms

Not cancerous. Benign tumors may grow larger but do not spread to other parts of the body. Also called nonmalignant.

The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

A benign condition in which there is a higher-than-normal level of a protein called M protein in the blood. Patients with monoclonal gammopathy of undetermined significance are at an increased risk of developing cancer. Also called MGUS.

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.

In medicine, a very simple microorganism that infects cells and may cause disease. Because viruses can multiply only inside infected cells, they are not considered to be alive.