Articles
The Hidden Driver of Cancer: How Infections Cause 1 in 8 Cases Worldwide
Introduction
When we think of cancer risk factors, lifestyle choices like smoking, diet, and sun exposure usually top the list. However, major global research points to another culprit that often goes unrecognised: infectious diseases.
A landmark study published in The Lancet Oncology shows that nearly one in eight new cancer diagnoses worldwide (12%) is directly attributable to treatable or preventable infections. That accounts for 2.3 million new cancer cases every single year.
In our latest podcast episode, we go through this research in detail, covering the major pathogens involved, global health disparities, and the steps the study sets out for cancer prevention.
Listen to the full podcast episode on Buzzsprout: Listen here
Access the original research article in The Lancet Oncology: Read the Lancet study
The scope: 12 pathogens and 2.3 million cancer cases
Analysing global cancer incidence data across 186 countries from the International Agency for Research on Cancer (IARC/WHO), researchers identified 12 infectious agents classified as Group 1 carcinogens that drive human malignancies.
Overall global cancer cases are projected to rise from 20 million in 2024 to 35 million by 2050 due to population ageing alone. Addressing infectious triggers is one of the most effective opportunities for targeted cancer prevention.
The vast majority of infection-attributable cancers are driven by five groups of pathogens:
- Helicobacter pylori (760,000 cases / 4% of all cancers): This stomach bacterium is the single largest infectious cause of cancer globally. It accounts for 85% of non-cardia stomach cancers (700,000 cases) and 74% of gastric MALT lymphomas.
- Human papillomavirus (HPV) (750,000 cases / 4% of all cancers): HPV drives 100% of cervical cancers (600,000 cases globally). High-risk strains HPV16 and HPV18 alone cause nearly three-quarters of all cervical cases. HPV also causes significant proportions of oropharyngeal, anal, penile, vaginal, and vulvar cancers.
- Hepatitis B virus (HBV) (360,000 cases) and Hepatitis C virus (HCV) (160,000 cases): These chronic viral infections are major drivers of liver malignancies, responsible for 52% and 20% of hepatocellular carcinomas, respectively.
- Epstein-Barr virus (EBV) (260,000 cases): Expanding epidemiological evidence now links EBV not only to nasopharyngeal carcinoma (where it drives 88% of cases) but also to 78,000 cases of gastric cancer and multiple lymphoma types, including Hodgkin lymphoma, diffuse large B-cell lymphoma, and Burkitt lymphoma.
- Kaposi’s sarcoma-associated herpesvirus (KSHV) (35,000 cases): Responsible for 100% of Kaposi’s sarcoma cases (34,000 cases) and primary effusion lymphoma.
Other carcinogenic microorganisms contribute thousands of cases annually. These include HIV (driving conjunctival cancer and increasing risk for HPV-, EBV-, and KSHV-related cancers through immunosuppression), HTLV-1 (3,900 cases of adult T-cell leukaemia/lymphoma), Merkel cell polyomavirus (3,200 cases), and parasitic infections like Schistosoma haematobium (5,900 bladder cancer cases) and liver flukes (Opisthorchis viverrini and Clonorchis sinensis).
Global disparities: low- and middle-income countries bear the brunt
Infection-attributable cancers do not affect the world equally. The study reveals stark global health inequities, with low- and middle-income countries bearing 77% of the total global burden.
- Eastern Asia records the highest absolute burden, with 990,000 cases (42% of the global total), heavily driven by high rates of H. pylori (410,000 cases) and Hepatitis B (260,000 cases).
- Sub-Saharan Africa experiences the highest proportional burden of HPV-driven cancers (14% population-attributable fraction) alongside elevated rates of KSHV and HIV-associated malignancies.
- Central and Eastern Europe faces substantial rates of both H. pylori and HPV-attributable cancers.
- Northern Africa sees a distinct cluster of Hepatitis C-driven liver cancers, primarily concentrated in Egypt.
Actionable solutions: vaccines, screening, and treatment
The most important message from the Lancet Oncology study is one of hope: infection-attributable cancers are among the most preventable malignancies in the world.
The public health strategies named in the research include:
- Vaccination: Expanding universal access to HPV vaccines (including single-dose regimens for adolescent girls and gender-neutral programmes) and neonatal HBV vaccines.
- Screening and early detection: Implementing population-level cervical and anal precancer screening, endoscopic or blood-based biomarker detection for gastric and nasopharyngeal cancers, and early detection programmes.
- Test and treat initiatives: Scaling up H. pylori screen-and-treat protocols, expanding access to direct-acting antivirals for Hepatitis C, and widening antiviral therapies for Hepatitis B and HIV.
- R&D investment: Prioritising clinical research into new prophylactic vaccines targeting EBV and KSHV.
Conclusion and podcast episode
Understanding the link between chronic infections and cancer opens up real opportunities for early intervention and prevention. By scaling up existing public health tools and investing in new research, millions of future cancer cases can be prevented globally.
Want to learn more about the science, data, and global health implications?
Tune into our full podcast episode now: Listen on Buzzsprout
Read the complete original article in The Lancet Oncology: Explore the study on The Lancet
