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Viruses and bacteria

The connection between infections and cancer is an important one. In developed countries, 7% of all cancer deaths are thought to be the result of viral and other infections.

Infectious agent Main types of cancer
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)

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. 

Many of the viral infections associated with cancers cause clearly identifiable non-cancerous conditions (or precancers) before developing into cancer. Screening tests can help identify these signs – and if they are treated successfully – cancer may be prevented. Screening using the Pap test has reduced the incidence of cervical cancer because precancerous changes were detected and treated early.

The incidence of infection-related cancers in the US, Canada and in developing countries is increasing because of the AIDS virus.

Currently, there are vaccines for only HBV (hepatitis B virus) and HPV (human papillomavirus). Reducing the risk of infection remains the best way to help prevent some infection-related cancers. For example, using condoms may help prevent HBV and HPV infection.

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