Pulse ·

One in eight cancers worldwide is caused by an infection

By Dr HB Lo, FACRRM 3 min read
Verdict Yes — worth knowing about

A global study estimates roughly one in eight cancers worldwide are attributable to infections. Major culprits: HPV (cervical, oropharyngeal and anal cancers), Helicobacter pylori (gastric cancer), and hepatitis B and C (liver cancer).

Australia has strong preventive infrastructure: the HPV vaccination programme, the National Cervical Screening Programme, universal HBV birth-dose immunisation, and H. pylori eradication therapy.

The question is not whether the tools exist — they do — but whether your vaccination and screening history is current. HPV status, a cervical screening test, and hepatitis B serology are reasonable starting points at 45.

You can prevent a cancer. Not in a vague, wellness-industry sense. Not through turmeric or a particular attitude or the right morning routine. In a specific, measurable sense: certain infections cause certain cancers, those infections are either preventable by vaccine or identifiable by test, and treatment in the right window dramatically reduces the downstream cancer risk. This is not a fringe observation — it describes roughly one in eight cancers diagnosed globally.

A new global study has quantified the infection-attributable cancer burden across 185 countries and 30 cancer sites. The finding: approximately 12.5% of all cancers — more than 2 million cases per year — are caused by infections. For Australia, a country with advanced preventive infrastructure, this number should be smaller. Whether it is depends on whether individuals have actually accessed that infrastructure.

What the study found

The major infection-cancer pairs are well established. HPV (human papillomavirus) drives virtually all cervical cancers and a growing proportion of oropharyngeal and anal cancers. Helicobacter pylori, a bacterium that colonises the gastric mucosa, causes the majority of gastric cancers. Hepatitis B and C viruses are responsible for most hepatocellular carcinoma globally. Epstein-Barr virus is implicated in certain lymphomas and nasopharyngeal cancers.

These are not rare exposures. HPV infects the majority of sexually active adults at some point in their lives. H. pylori colonises roughly half the world’s population. Hepatitis B remains endemic across much of Asia and Africa, and in Australia it is disproportionately prevalent in people born in those regions.

The study does not change what we know about these infections or their cancer associations. What it does is put the population-level scale of the problem in one place — and, in doing so, make legible the question: which of these is part of your picture?

Both sides of this

The reassuring reading: Australia is genuinely well-positioned. The national HPV vaccination programme has been running since 2007 for girls and 2013 for boys, and the 9-valent Gardasil 9 has been on the programme since 2018. The National Cervical Screening Programme switched from Pap smears to HPV DNA testing in 2017, dramatically improving sensitivity. Universal HBV birth-dose vaccination has been in place since the 1980s. H. pylori eradication is accessible and effective.

The less reassuring reading: these systems only work for the people who have actually accessed them.

Women who were born before 2007, or who were outside the school programme age range when vaccination rolled out, may have partial or no HPV vaccine coverage. Women who have not had a cervical screening test in the past five years are outside the detection window. People born in high-prevalence HBV countries may be carrying chronic infection without knowing. People with chronic dyspepsia who have never been tested for H. pylori may be in that long, slow erosion phase that precedes gastric cancer by decades.

The headline figure of one in eight cancers is a population average. The individual question is more specific.

What this means for you this week

For a woman in her mid-forties reviewing her cancer risk, the infection-attributable cancers are a practical checklist:

HPV: When was your last cervical screening test? The current schedule is every 5 years after a first normal result (or 12 months after an HPV-positive result that self-clears). If you are overdue, book it. If you did not receive the HPV vaccine in school and are under 45, catch-up vaccination is available and PBS-subsidised for adults — ask your GP.

H. pylori: If you have recurring bloating, heartburn, or upper abdominal discomfort that comes and goes, and have never been tested, a breath test or stool antigen test is a reasonable ask. If there is a family history of stomach cancer or ulcers, even stronger reason.

Hepatitis B: If you were born outside Australia — or if you are simply not certain of your HBV vaccination status — a surface antigen and antibody check is a single blood test that your GP can add to any standard review. If you have chronic HBV infection, regular monitoring and antiviral therapy where indicated substantially reduces liver cancer risk.

These are not difficult asks. They are the kind of question you deserve to be able to bring to your GP and have answered in the actual context of your history — not with a “you’re probably fine” that does not account for where you grew up, what school programme you were in, or what your family carries.

Verdict: yes — worth knowing about.

Sources cited

  1. One in eight cancers are likely caused by an infection worldwide — The Conversation AU, 29 September 2026. https://theconversation.com/one-in-eight-cancers-are-likely-caused-by-an-infection-worldwide-new-research-292996

Frequently asked questions

  • Which cancers are linked to HPV and am I at risk?

    HPV is the leading infection-attributable cancer cause globally, responsible for virtually all cervical cancers and a growing proportion of oropharyngeal (throat) and anal cancers. In Australia, the 9-valent HPV vaccine (Gardasil 9) has been part of the school immunisation programme since 2013 for girls and 2013–2016 for boys, expanded to all genders. Women who completed the vaccine programme and remain current on the cervical screening test (every 5 years after a first negative result) have substantially reduced risk. If you are over 30 and unsure of your vaccination history, speak to your GP — catch-up vaccination is available for adults up to 45 years.

  • What is H. pylori and should I be tested for it?

    Helicobacter pylori is a bacterium that colonises the stomach lining. It is very common — infecting roughly half the world's population — and most people carry it without symptoms. In a subset of people, chronic infection causes gastric ulcers and, over decades, can progress to gastric cancer. Testing is straightforward (a breath test or stool antigen test, or serology) and eradication therapy is highly effective. If you have a family history of stomach cancer or ulcers, recurring dyspepsia, or have not been tested, this is worth raising with your GP.

  • What about hepatitis B and liver cancer?

    Hepatitis B virus (HBV) is one of the world's leading causes of hepatocellular carcinoma (liver cancer). In Australia, universal birth-dose HBV vaccination has been in place since the 1980s and HBV is now rare in the Australian-born population. However, people born overseas — particularly in Southeast Asia, China, sub-Saharan Africa, and the Pacific — may have been born before comprehensive vaccination programmes were in place and may carry chronic HBV infection without knowing. If you were born overseas or are unsure of your HBV status, a blood test through your GP can confirm your surface antigen and antibody status.