There is no clear cause of multiple myeloma. Scientists are working to discover potential causes and have identified different factors that increase a person’s chance of developing the condition. Several different viral infections have been highlighted as possible risk factors for multiple myeloma.

There is no evidence that viral infections cause myeloma. However, viruses are a source of interest in trying to understand this disease and discovering what causes it. This is because research studies have found that people with multiple myeloma have higher frequencies of certain viral infections as compared to those without multiple myeloma. Viruses are also of interest because of how they work and cause other types of cancer.

Most people who experience viral infections will not develop conditions like multiple myeloma. Viruses possibly connected to myeloma include:

• HIV
• Hepatitis C virus (HCV)
• Human herpesvirus 8 (HHV-8)

These viruses are thought to play a role in the development of multiple myeloma through the processes that occur in the cells of the body when it’s infected with a virus. Different viruses work in distinct ways to influence the development of myeloma.

Although having risk factors for multiple myeloma may increase someone’s chance of developing the condition, many people with multiple myeloma have no known risk factors for it. There is still a lot to be discovered in understanding the true causes and mechanisms of multiple myeloma.

If you are showing symptoms or believe you have been exposed to one of the viruses discussed in this article, contact your health care provider. A blood test may be used to determine if you have a virus. Starting treatments like antivirals earlier helps to reduce symptoms and complications from these viruses. Research discovering new therapies for viruses and diseases involving the immune system is ongoing.

Multiple Myeloma

Multiple myeloma is a type of cancer that starts with an abnormal white blood cell, or plasma B cell, in the bone marrow. In many cases, it starts as a condition called monoclonal gammopathy of undetermined significance (MGUS). Healthy plasma cells make proteins called antibodies that help fight infections. When these cells have abnormalities, they start creating abnormal antibodies called monoclonal proteins (also called M protein).

In people with multiple myeloma, the abnormal plasma cells multiply and accumulate. This process crowds out the growth of healthy plasma cells, affects the immune system, and could lead to cancer.

Viral Infections and Multiple Myeloma

It’s not clear what causes a plasma cell to become abnormal in multiple myeloma, but viral infections have been identified as potentially playing a role in this process. Viruses are considered infectious diseases, and when they enter the body, they spread their DNA or RNA. This process can affect and alter the DNA of healthy cells. Some viruses interrupt the healthy process of cell growth, which can lead to uncontrolled cell growth and cause cancer. Viruses also affect the body’s immune system and its ability to fight off other types of infections like bacterial and fungal infections.

The research exploring the potential connections between viral infections and multiple myeloma is ongoing. Scientists aren’t certain whether viral infections are a definite risk factor for myeloma, but some oncology (cancer) research studies have observed an increased incidence (frequency) of certain viruses in people who have multiple myeloma.

Human Immunodeficiency Virus

HIV weakens the immune system and makes the body more susceptible to infection and disease. There is no cure for HIV, which is a lifelong infection that lives in the body. It is spread through activities considered “high-risk,” like having unprotected sex and sharing needles for drug injection. People living with HIV have a higher risk of other types of cancers like Kaposi sarcoma, lymphoma, leukemia, and cancers of the lung, liver, cervix, anus, and throat.

Research has found that disorders of plasma cells, including MGUS — a risk factor for multiple myeloma, are common in young people with HIV.

One study found that people with HIV are more than four times as likely to develop multiple myeloma as compared to those without HIV. However, the study could not say whether HIV infection was a risk factor for developing multiple myeloma.

HIV infection can also lead to AIDS, which greatly reduces the immune system’s ability to fight off infections and diseases. Research has found that people with AIDS have an increased risk of different types of cancer, with an approximate 12 percent increased risk of multiple myeloma, as compared to people who do not have AIDS. It is unclear what role AIDS plays in the development of multiple myeloma and whether the connection is a severely compromised immune system or another factor.

Hepatitis C and Hepatitis B Viruses

HCV spreads through the blood and can cause liver cancer. HCV has been identified as a possible risk factor for multiple myeloma, but the research on this topic is ongoing. Some research studies have found that people with HCV have an increased risk of developing multiple myeloma, but other studies have not found the same result.

Hepatitis B (HBV) has also been linked to liver infections and liver cancer. Most children in the United States receive routine vaccinations against HBV, so the prevalence (number of cases) of HBV is lower in this country, and there is a lower risk of infection.

Research studies on hematology (the study of blood disorders) have found higher rates of HBV in people with multiple myeloma. However, this is only seen as a potential association, and further evidence is needed to confirm a connection between HBV and myeloma.

Human Herpesvirus 8

HHV-8, also called Kaposi sarcoma-associated herpesvirus, is a virus that affects the cells that line blood and lymph vessels. It is less common in the United States, where it is believed to be spread mainly through sexual contact. HHV-8 has been connected to lymphoma, a cancer of the lymph nodes, and scientists are exploring whether it could also be associated with multiple myeloma.

The results of research studies exploring a connection between HHV-8 and multiple myeloma have been mixed. Some studies have found that people with multiple myeloma have also tested positive for HHV-8 in their blood, but this does not prove any connection between the conditions.

A large study conducted in 2005 examined more than 1 million people and found no connection between HHV-8 infection and the risk of multiple myeloma.

Other Multiple Myeloma Risk Factors

Scientists believe that viral infections are only a possible risk factor in determining a person's susceptibility to developing multiple myeloma. There are other genetic and lifestyle factors that researchers have determined are connected to the risk of multiple myeloma. However, it’s important to remember that presence of these factors does not mean someone will definitely develop multiple myeloma.

Risk factors for multiple myeloma are higher for Black people, older people, and men. They also include:

• Having MGUS
• Obesity
• Working on a farm (exposure to certain pesticides and chemicals)
• Family history of multiple myeloma

Talk With Others Who Understand

MyMyelomaTeam is the social network for people with multiple myeloma. On MyMyelomaTeam, more than 14,000 members come together to ask questions, give advice, and share their stories with others who understand life with multiple myeloma.

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