8 viruses that cause cancer

Researchers know that several infections can lead to cancer. This includes infections caused by bacteria, fungi and viruses.

Studying infections and cancer helps researchers develop vaccines and other ways to reduce cancer risk, including early identification and treatment of viruses that cause cancer. We spoke with infectious disease specialist Harrys Torres, M.D., to learn more.

What is a virus?

Viruses are very small organisms. They are made up of genes – DNA or RNA – surrounded by a protein coating. Viruses require the cells of living hosts, such as people, to survive.

How do viruses cause cancer?

Viruses have a complicated effect on cancer development. Experts don’t fully understand all the ways some oncoviruses cause cancer. What we do know is that viruses hijack cells and insert their DNA or RNA into the host cell. This can cause the host cells to become cancerous.

There are several oncoviruses, or viruses that cause cancer.

Epstein-Barr virus (EBV)

Epstein-Barr virus is a herpes virus that’s spread through saliva. EBV infection increases the risk of Burkitt lymphoma, some types of Hodgkin and non-Hodgkin lymphoma, and stomach cancer. There is currently no vaccine for Epstein-Barr virus.

Hepatitis B virus (HBV)

Hepatitis B virus is spread through infected blood, semen and other body fluids. HBV is a leading cause of liver cancer. It is recommended that all infants be vaccinated against HBV at birth and complete the vaccination series within six to 18 months. Anyone who was not vaccinated at birth should get vaccinated. Talk to your doctor if you are not sure if you’ve been vaccinated.

For some patients who are chronically infected with HBV, antiviral treatment against HBV decreases the risk of developing hepatocellular carcinoma, a type of liver cancer. Get screened for HBV, and if you have it, talk to your doctor about treatment recommendations.

Hepatitis C virus (HCV)

Hepatitis C virus is spread through infected blood. HCV is a leading cause of liver cancer, and it can cause non-Hodgkin lymphoma. There is no vaccine against HCV, but it is treatable.

Antiviral treatment can cure HCV and decrease your risk of developing hepatocellular carcinoma. Get screened for HCV, and if you have it, talk to your doctor about treatment recommendations.

Human immunodeficiency virus (HIV)

HIV is spread through infected semen, vaginal fluids, anal fluids, blood and breast milk. While it does not cause cancer directly, researchers believe it increases the risk of cancer by damaging the immune system, which reduces the body’s defenses against other oncoviruses. It can enable other oncoviruses to cause cancer. HIV-associated cancers include:

• Kaposi sarcoma,
• non-Hodgkin and Hodgkin lymphoma,
• cervical cancer,
• anal cancer,
• liver cancer,
• oral cancer,
• throat cancer and
• lung cancer.

There is no vaccine against HIV, but there is effective antiretroviral therapy to treat HIV and to help lower your risk of HIV-associated cancers.  

Kaposi sarcoma-associated herpesvirus (KSHV)

Kaposi sarcoma-associated herpesvirus is also known as human herpesvirus 8 (HHV-8). This virus can cause Kaposi sarcoma in people with a weakened immune system. That includes patients with HIV. HHV-8 can also cause some types of lymphoma.

Human papillomavirus (HPV)

HPV has at least 12 strains that can cause several types of cancer in men and women, including:

• anal cancer,
• cervical cancer,
• penile cancer,
• throat cancer,
• vaginal cancer and
• vulvar cancer.

All people ages 9–26 should get the HPV vaccine. Unvaccinated men and women ages 27–45 should talk to their doctor to see if the vaccine may be beneficial for them.

Human T-cell leukemia virus type 1 (HTLV-1)

Human T-cell leukemia virus type 1, also known as human T-cell lymphotropic virus type 1, is linked to adult T-cell leukemia and lymphoma. It is spread through infected semen, vaginal fluids, blood and breast milk. The infection is rarely found in the United States. There is currently no vaccine for HTLV-1.

Merkel cell polyomavirus (MCV)

Merkel cell polyomavirus is a virus that can cause Merkel cell carcinoma, a rare and aggressive type of neuroendocrine tumor that forms in the skin. Experts are still learning about this virus, but it is believed to spread through direct contact with the skin. Currently, there is no vaccine for MCV.   

What can people do to avoid getting these cancer-causing viruses?

Here are ways to reduce your risk of getting oncoviruses.

• Get vaccinated. The HPV vaccine can help prevent cervical cancer, anal cancer, vaginal cancer and vulvar cancer, and it can help lower your risk of getting HPV-related cancers of the throat and penis. The hepatitis B vaccine can help reduce your liver cancer risk.
• Get screened. Screening is available for some cancer-related viruses, like HPV, HIV and hepatitis B and C. If you’re at risk, get screened. In addition, follow our cancer screening guidelines. Screening is one of the best ways to catch cancer early when it’s easiest to treat. Talk to your doctor to learn if you need earlier or additional screening.
• Practice safe sex. HPV, HIV, HTLV-1, hepatitis B and hepatitis C can be sexually transmitted.
• Don’t share needles or syringes. Don’t share syringes, needles or other infected equipment or personal items that might have blood on them. This reduces your risk of developing blood-borne viruses, such as hepatitis B and C and HIV.

If you think you may have or be at risk for an oncovirus, talk to your doctor about how to lower your cancer risk.

Request an appointment at MD Anderson online or call 1-833-987-1744.