Certain infections can cause cancer. Some viruses, bacteria and other infectious agents (such as parasites) have been linked to an increased risk of cancer in children and adults. Most of these infections are preventable. In developed countries, about 7% of all cancer cases are thought to be the result of infections. The percentage is much higher in less developed countries.
Some viral or bacterial infections may change cells in some way. These changes may damage DNA, suppress the immune system or cause long-term inflammation. These changes may also lead to a higher risk of certain cancers.
The International Agency for Research on Cancer (IARC) classifies some infection-causing agents as known carcinogens. Examples of infection-causing viruses, bacteria and other infectious agents associated with cancer are listed in the table below.
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Epstein-Barr virus (EBV) | nasopharynx, Hodgkin lymphoma, non-Hodgkin lymphoma |
Helicobacter pylori (H. pylori) | stomach |
hepatitis B virus (HBV), hepatitis C virus (HCV) | liver |
human herpes virus 8 (HHV8) | Kaposi sarcoma, non-Hodgkin lymphoma |
human immunodeficiency virus (HIV) | Hodgkin lymphoma, non-Hodgkin lymphoma, Kaposi sarcoma |
human papillomavirus (HPV) | cervix, anus, vagina, vulva, penis, oropharynx |
human T-cell leukemia/lymphoma virus type 1 (HTLV-1, human T-cell lymphotropic virus type 1) | adult T-cell leukemia/lymphoma (ATL/L) |
Opisthorchis viverrini (O. viverrini) (liver fluke) | bile duct |
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Although these infections may increase a person’s risk of developing cancer, many people with these infections do not develop cancer. Other factors also affect the risk of developing cancer.
Infections are also associated with some precancerous conditions. Early detection and screening can help identify precancerous conditions. Cancer may be prevented if these conditions are treated successfully.
Reducing your risk
Take steps to reduce your risk of infection. This is the best way to help prevent some infection-related cancers.
You can also reduce your risk by getting vaccinated against HPV and hepatitis B.