In Australia around 3.3% of all cancers are caused by infections. Normally our immune system is good at getting rid of, or clearing, infections from our body. But sometimes our immune system finds it hard to do this so an infection stays in the body for a long time. This is called chronic or persistent infection. In a small number of people, chronic or persistent infection can lead to the development of cancer. How this happens is not fully understood, but there is evidence that chronic infections can:
- damage the DNA in our cells, which can lead to cancer
- cause inflammation, which causes cells to rapidly divide and can lead to cancer.
There are a number of common viruses, bacteria and parasites that are linked to cancer:
Type of infection
Cancer associated with this infection
|Human papillomavirus (HPV)||Cervical cancer
Head and neck cancers (aka oropharyngeal cancer including cancer of the base of the tongue, tonsils, or upper throat)
|Hepatitis B virus (HBV)||Liver cancer - Hepatocellular carcinoma (HCC)|
|Hepatitis C virus (HCV)||Liver cancer - Hepatocellular carcinoma (including cholangiocarcinoma)
Non-Hodgkin lymphoma (NHL)
|Human herpesvirus 8 (also known as Kaposi sarcoma herpesvirus)||Kaposi's sarcoma
Primary effusion lymphoma, a type of blood cancer which is a rare complication occurring mainly among people with HIV
|Human T-cell lymphotropic virus 1||Adult T-cell leukaemia and lymphoma|
Epstein-Barr virus (EBV)
Natural Killer/T-cell lymphoma
|Human immunodeficiency virus (HIV) 1||Cervical cancer
Conjunctiva cancer (in the eye)
|Merkel cell polyomavirus (MCV)||Merkel cell carcinoma (MCC), a rare but aggressive type of skin cancer|
|Helicobacter pylori||Stomach cancer (Non-cardia gastric carcinoma
B-cell MALT gastric cancer)
|Liver flukes (Opisthorchis viverrine; Clonorchis sinensis)||
Bile duct cancer (Cholangiocarcinoma a type of liver cancer)
Reference: IARC Mongraph Vol 100B, 2012
What can I do?
If you can, you should vaccinate against infection. Vaccines are available to prevent infection with some, but not all, cancer-causing human papillomaviruses, and hepatitis B virus.
There are effective treatments - called antiviral therapies - for people who have been infected with hepatitis B, human immunodeficiency virus 1 and hepatitis C. There are also effective treatments available for H. pylori, liver flukes and schistosomiasis, which is a parasitic disease caused by Schistosoma haematobium.
Human papillomavirus, or HPV, is a common virus that affects both males and females. There are more than 100 types of HPV. Certain types of HPV cause common warts on the hands and feet. Most types of HPV are harmless, do not cause any symptoms, and go away on their own.
About 40 types of HPV are known as genital HPV as they affect the anal and genital area. Genital HPV is spread by intimate skin to skin contact and skin to mucosa contact, including sexual intercourse. HPV infection is most common in the early years of sexual activity or with a new sexual partner. Both men and women can get HPV. Most women and men will have had at least one type of genital HPV in their lifetime.
HPV is the most common sexually transmitted infection among women and men. Eight out of ten men and women will be infected with at least one type of HPV at some time in their life.
Genital HPV types may be ‘low-risk' types (such as HPV types 6 and 11) or ‘high-risk' types (such as HPV types 16 and 18). ‘Low-risk' HPV types can cause genital warts. ‘High risk' types 16 and 18 are responsible for 70% of cervical cancers. ‘High-risk' HPV have also been linked with cancers of the mouth, head and neck (base of the tongue, tonsils, or upper throat), anus, penis, cervix, vagina and vulva.
Long-term infection (also known as chronic or persistent infection) with high-risk HPV types can result in the development of cancer. Cancer is a rare complication of high-risk HPV infection. It is important to remember that most people who become infected with HPV will not develop cancer.
Gardasil 9 is a new HPV vaccine introduced in 2018, it protects against seven high-risk HPV types (16, 18, 31, 33, 45, 52, and 58) which cause about 90% of cervical cancers in women and at least 90% of all HPV-related cancers in men. It also protects against two low-risk HPV types (6 and 11) which cause 90% of genital warts. So being vaccinated has the potential to prevent most cervical and other cancers and most cases of genital warts.
Australia's National Human Papillomavirus vaccination program began in 2007 to protect girls and young women against HPV infections that can lead to cervical cancer. In 2013 boys were added to the program. HPV vaccination is part of the school vaccination schedule for all girls and boys aged 12-13 years. In Western Australia the vaccination is given in year 8.
If you are a woman who has been vaccinated against HPV, it is important that you still have regular cervical screening.
Hepatitis B virus (HBV) is one of the most serious infections and is the second most common carcinogen after tobacco worldwide. HBV is highly contagious and in Australia is most commonly transmitted at birth from an infected mother to the baby. Exposure to infected blood or other body fluids including blood products, contaminated needles (hypodermic, tattooing), semen, vaginal fluid, saliva, breast milk and sweat can cause viral transmission. HBV infection is considered to be ‘acute' during the first six months after infection. If HBV tests (HBsAg) are positive after six months, then a person is considered to have ‘chronic' HBV infection which will remain for the rest of an individual's life. The majority of chronic cases occur in people that are infected during birth or childhood and most acute cases occur when infected in adulthood. Acute HBV usually resolves by itself but it is necessary to monitor for six months to ensure it does not develop into chronic infection. Chronic HBV infection greatly increases the chances of developing liver cancer if left undiagnosed and untreated.
There are over 210,000 people in Australia living with chronic HBV infection yet nearly half of those living with chronic HBV in Australia are undiagnosed (not tested). Most of HBV infections in Australia are found in people that come from countries with high rates (prevalence) of HBV including Asia Pacific region and Sub-Saharan African (see map below) as well as Aboriginal and Torres Strait Islander people who are at higher risk of developing HBV.
Distribution of hepatitis B virus around the world
HBV infection is preventable through vaccination. A vaccine for HBV is available and is recommended for all babies and adolescents in Australia, as well as adults who are at risk of HBV infection. This includes migrants from areas with high rates of HBV (see map above) and Aboriginal and Torres Strait Islander people.
HBV infection can also be prevented by avoiding contact with infected blood or body fluids through safe medical, dental, transfusion and injection practices and incorporating the use of condoms.
Safe and effective anti-viral treatments are available for people infected with HBV and have been shown to reduce their risk of developing liver cancer. Without medical treatments, 1 in 4 people living with chronic hepatitis B will die prematurely from liver cancer or liver failure.
If you come from a country that has high rates of HBV, are at risk of infection, or if you are unaware of your immunisation status, speak to your GP about hepatitis B testing.
To learn more about hepatitis B, download our Hepatitis B and Liver Cancer Fact Sheet (pdf 716kb).
This factsheet has also been developed in other languages by Cancer Council South Australia and adapted by Cancer Council Western Australia. The factsheet is available in:
Hepatitis C virus (HCV) is transmitted by exposure to infected blood or blood products and contaminated needles (hypodermic, tattooing). People infected with chronic HCV are at increased risk of developing liver cancer.
There are over 230,000 people in Australia living with chronic HCV. Over 80 percent of new HCV cases are a related to sharing of injecting drug equipment; the remaining cases are caused by unsterile tattooing, body piercing procedures, medical procedures and vaccination and needle-stick injuries.
In Australia, around 20 percent of people living with HCV remain undiagnosed and less than 2 percent are accessing treatment. If left untreated, majority of chronic HCV infections will develop into chronic liver disease and 1-5 percent of infections will develop into liver cancer.
There is no vaccination available for HCV but HCV infection can be prevented by avoiding contact with infected blood through safe medical, dental, transfusion and injection practices.
Safe and highly effective anti-viral treatments are now available and are part of the Pharmaceutical Benefits Scheme (PBS), making them accessible and affordable for people living with chronic HCV. They have been shown to greatly reduce the risk of developing liver cancer and other liver-related diseases.
If you have a history of unsafe injecting drug use, or are concerned about your HCV status, speak to your GP about hepatitis C testing.
Human Herpesvirus 8 (HHV8) is a common infection, primarily transmitted by saliva. HHV8 is also known as Kaposi's Sarcoma Associated Herpesvirus (KSHV) as it has been linked to Kaposi's sarcoma, a rare type of cancer. People who are immune suppressed (HIV patients, organ transplant patients) are at higher risk of developing this cancer. HHV8 has also been associated with Primary Effusion Lymphoma, a type of blood cancer which is a rare complication occurring mainly among people with HIV.
There is no vaccination available for HHV8, however there are treatments available for people with HHV8 infection.
Epstein-Barr Virus (EBV) is more commonly known as Glandular fever and is transmitted by mouth, such as kissing, sharing eating utensils and drinks or pre-tasting food (eg for infants). EBV infection is common and usually causes no long term problems. However, very rarely it can cause certain types of lymphoma, including Burkitt's lymphoma, Hodgkin's lymphoma and Non-Hodgkin's lymphoma.
EBV is also strongly linked to Burkitt's lymphoma, a common childhood cancer in central Africa and Papua New Guinea. Many children in these countries have chronic malaria infection, which reduces their resistance to infection from EBV. Organ transplant patients infected with EBV have an increased risk of developing certain types of lymphoma as a result of immunosuppression. EBV infection also causes nasopharyngeal cancer, a type of cancer most common in South East Asia.
There is no vaccination available for EBV, however there are effective treatments available for people infected with EBV.
People with Human immunodeficiency virus 1 (HIV) and acquired immunodeficiency syndrome (AIDS) have weakened immune systems and are at risk of developing a number of cancers, including Kaposi's sarcoma, Hodgkin's lymphoma, non-Hodgkin's lymphoma, anal cancer and cervical cancer.
People who have unprotected sex with multiple partners, who inject drugs and share injecting equipment, and infants of mothers infected with HIV are at increased risk of HIV infection.
There is no vaccination available for HIV, however there are effective retroviral treatments available for people with HIV infection.
WA Aids Council is a valuable resourse for people in WA who are living with HIV and AIDS.
Helicobacter pylori (H.pylori) is a bacterium that causes ulcers in the stomach and duodenum (the first section of the small intestine). Long-term infection with H.pylori can lead to stomach cancer and a rare type of lymphoma called low-grade B-cell MALT gastric lymphoma.
H.pylori is a common infection in people, and is spread by saliva and possibly faecal waste (poo). Most people are infected as children.
Some people with H.pylori infection have no symptoms. The most serious symptoms are upper gastric discomfort and ulcers. Cancer only occurs in a small number of people who are infected with H.pylori. There are effective treatments available for people infected with H.pylori.
Schistosomes haematobium (blood flukes) are parasitic blood dwelling flatworms found mainly in sub-Saharan Africa. Infection occurs after direct contact with fresh water that contains newly hatched Schistosoma haematobium worms. Schistosomiasis is a parasitic disease caused by Schistosomes haematobium. Long term infection causes bladder cancer.
There are effective and safe treatments available for Schistosomes haematobium.
Liver flukes - Opisthorchis viverrine; Clonorchis sinensis - are a type of parasite. People can become infected with liver flukes from eating raw or undercooked fresh water fish. Infection with liver flukes is common in Asian countries, including Thailand, China, Republic of Korea, Laos and Cambodia. Most people have no symptoms, but people with severe infections may have fatigue, pain in their abdomen or jaundice. Long-term infection with liver flukes can cause cholangiocarcinoma, a type of liver cancer.
There are effective and safe treatments available for liver flukes.