Viruses that Can Lead to Cancer

HBV, HCV, and HDV can cause chronic (long-term) infections that increase a person’s chance of liver cancer. Some recent research also suggests that these viruses might be linked with some other cancers, such as non-Hodgkin lymphoma.

HBV, HCV, and HDV can be spread from person to person through unprotected sex, childbirth, or sharing needles, such as during the use of injected drugs. They can also be passed through blood transfusions, but this is rare in the US because donated blood is tested for these viruses.

HBV might cause symptoms such as a flu-like illness and jaundice (yellowing of the eyes and skin). Most adults recover completely from HBV infection within a few months. However, people with chronic HBV infections have a higher risk of liver cancer. Only a small portion of adults infected with HBV go on to have chronic HBV infections, but this risk is higher in young children.

HCV is less likely to cause symptoms than HBV, so many people do not know that they have been infected. If it is not treated, more than half of people who get HCV develop chronic infection, which can lead to serious liver problems or cancer.

HDV can cause symptoms that are more severe than those caused by HBV alone, such as dark urine, clay-colored stools, and joint pain.

The US Centers for Disease Control and Prevention (CDC) recommends that all people 18 years of age or older get tested for HBV and HCV at least once during their lifetime to look for unknown chronic infections. Testing is also advised for all pregnant people. The CDC also recommends testing for HDV if symptoms are noticed.

Some high-risk groups of people might be advised to get tested at a younger age and more often, including:

• People living with HIV
• Men who have sex with men
• People who inject drugs
• People in certain group homes
• People with certain medical conditions
• Healthcare workers who might be exposed to blood on the job

The CDC has more information about who should get tested for HBV, HCV, and HDV and how often.

If an infection is found, treatment and preventive measures can be used to slow liver damage and reduce cancer risk.

Treating chronic HCV infection with a combination of drugs for at least a few months can cure most people.

Several drugs can be used to help treat chronic HBV and HDV infections. Although they don’t cure the disease, they can lower the risk of liver damage and might lower the risk of liver cancer as well.

There is a vaccine to prevent HBV infection, but not one for HCV. The vaccine to prevent HBV also protects against HDV.

For a complete list of who should get the HBV vaccine, see the Recommendations for HBV Vaccination on the CDC website.

EBV mainly spreads through saliva. In addition to kissing, EBV can be spread by sharing drinks, food, eating utensils, or toothbrushes. It might also spread through sex, blood transfusions, or organ transplants, but this is much less common.

Most people are infected with EBV at some point in their lives, often in childhood or adolescence. Worldwide, more than 90% of people have been infected with EBV.

Many people never develop symptoms after EBV infection. When symptoms of mono do occur, people usually feel better in 2 to 4 weeks, although fatigue can last longer.

EBV infection is lifelong. After infection, EBV remains in a person’s B cells (immune system cells) and usually stays inactive (latent).

Though most EBV infections cause only mild illness, EBV can sometimes lead to more serious health problems, especially in people with weakened immune systems. There is currently no treatment that gets rid of the virus and no approved vaccine to prevent EBV infection, although vaccines are being studied.

Though most people infected by EBV will not develop cancer from it, EBV infection increases a person’s risk of getting some cancers, including nasopharyngeal cancer and certain types of fast-growing lymphomas, such as Burkitt lymphoma. It might also be linked to Hodgkin lymphoma and some cases of stomach cancer. Researchers continue to study EBV to find links to cancer and other diseases.

HHV-8 can spread through sexual contact and might also spread through blood and saliva. HHV-8 infection is lifelong. In the US, less than 10% of people are infected with this virus, and most people do not show any symptoms.

Infection with HHV-8 can cause cells that line blood and lymph vessels to grow and live longer than normal, which can sometimes lead to Kaposi sarcoma over time. KS is a rare, slow-growing cancer that often appears as red, purple, or brown lumps or patches on the skin. It can also affect cells that line the blood and lymph vessels.

Most healthy people who are infected with HHV-8 don’t get KS. Other factors, such as a weakened immune system, are needed for it to develop. For example, KS is more common in people who’ve had an organ transplant. Historically, KS was seen more frequently in people living with HIV, but this has become less common because of better HIV treatments (antiretrovirals).

HHV-8 infection has also been linked to some other rare blood diseases:

• Primary effusion lymphoma
• Multicentric Castleman disease, which can lead to lymphoma

More research is needed to better understand how HHV-8 might cause these diseases.

HTLV-1 is passed from person to person through blood and body fluids. Since 1988, all donated blood in the US is screened for HTLV-1, which has greatly reduced the chance of infection through blood transfusions.

Most people with HTLV-1 never have symptoms, but in rare cases it can cause health problems other than cancer.

Learn more about HTLV-1 from the World Health Organization (WHO).

HTLV-1 can change how the cell it infects grows and divides. This can sometimes lead to a rare cancer called adult T-cell leukemia/lymphoma (ATL), a type of non-Hodgkin lymphoma. Usually after at least 20 years of infection, a small percentage of people with HTLV-1 might progress to ATL. 

Research suggests that the virus can shed from the skin of infected people and spread to others.

MCPyV was found in 2008 in samples from a rare and aggressive type of skin cancer called Merkel cell carcinoma (MCC). Most cases of MCC are now thought to be linked to MCPyV infection. In rare cases, MCPyV can affect the DNA inside cells, which can lead to this type of cancer.

Learn more about Merkel Cell Skin Cancer.

SV40 is a virus that usually infects monkeys. It was introduced to humans between 1955 and 1963 through some polio vaccines that were contaminated with SV40. Other causes of infections in people are rare and mostly seen in people who are near monkeys that carry the virus.

Some older research suggested that infection with SV40 might increase a person’s risk of developing a rare cancer called mesothelioma. Newer research has not found any increased risk. Other risk factors, such as exposure to asbestos, are much more important in causing mesothelioma.

Older studies have suggested a link between SV40 infection and some brain tumors, bone cancers, and lymphomas. However, the findings are not certain.

Although SV40 has been shown to cause cancer in some lab animals, current evidence has not yet shown a direct cause of cancer in people.