Around one in eight cancer cases worldwide in 2024 was attributable to infections, according to a World Health Organization (WHO) study highlighting the role of preventable and treatable pathogens in the global cancer burden.
The research, published in The Lancet Oncology, estimated that infections accounted for approximately 2.3 million new cancer cases during the year, representing about 12 per cent of the global total.
Five pathogens were responsible for most of these cases: Helicobacter pylori (H. pylori), human papillomavirus (HPV), hepatitis B virus, Epstein-Barr virus and hepatitis C virus.
H. pylori and HPV each accounted for around four per cent of global cancer cases, while hepatitis B was linked to approximately two per cent. Epstein-Barr virus contributed around one per cent, with hepatitis C accounting for less than one per cent.
The findings underline how infections can contribute to several forms of cancer, including stomach, liver, cervical and blood cancers. Around 75 per cent of infection-attributable cases occurred in low- and middle-income countries, highlighting differences in access to vaccination, screening and treatment.
How can infections lead to cancer?
Infections can contribute to cancer through different biological mechanisms. Some viruses interfere with the normal functioning of cells, alter genetic material or disrupt proteins that help prevent uncontrolled cell growth. Others can integrate their genetic material into human cells or carry genes that encourage tumour development.
Long-term bacterial and parasitic infections can also increase cancer risk. Persistent inflammation and tissue damage may lead to changes in DNA and errors during cell division.
H. pylori, a bacterium commonly associated with stomach ulcers, is linked to stomach cancer. The liver fluke Opisthorchis viverrini is another example of a parasite associated with cancer, particularly bile duct cancer.
However, infection does not mean that a person will necessarily develop cancer. The risk varies according to the pathogen, the duration of infection and other individual and environmental factors.
What can be done to prevent infection-related cancers?
Vaccination, screening and timely treatment are among the main ways to reduce cancers associated with infections.
The HPV vaccine protects against strains responsible for most cervical cancer cases. Australia's vaccination programme, introduced in 2007, has been associated with a 90 per cent reduction in HPV infections among eligible people. The country is also working towards eliminating cervical cancer as a public health problem by 2035.
However, vaccination coverage remains a concern. The proportion of 15-year-olds in Australia who had received the HPV vaccine fell from 85.7 per cent in 2020 to 79.5 per cent in 2024. The WHO target is to vaccinate 90 per cent of girls by the age of 15 by 2030.
Research has also highlighted the impact of vaccination on cervical cancer deaths. A UK study found that HPV vaccination brought cervical cancer deaths to zero among women under 30, underlining the importance of maintaining high coverage.
Other measures include screening for cervical cancer, using condoms to reduce the risk of sexually transmitted infections, and diagnosing and treating hepatitis B and C, H. pylori and HIV.
In England, the NHS has also been expanding access to HPV vaccination and screening. The NHS is rolling out home-testing kits to increase cervical cancer screening uptake, while pharmacists have been urged to play a greater role in promoting cervical screening.
The National Cancer Plan also outlines an expanded role for community pharmacies, including support for HPV vaccination and earlier identification of potential cancer symptoms.
Access to these interventions remains uneven, particularly in lower-income countries where healthcare infrastructure, diagnostic services and vaccination programmes may be limited.
The study adds to evidence that a substantial share of the global cancer burden is associated with infections that can be prevented, detected or treated. Improving access to these interventions could therefore form an important part of wider cancer prevention strategies.
