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The session titled “Defeating Cancer by Curing Infections” at European Society of Clinical Microbiology and Infectious Diseases Global 2025, held in Vienna, Austria, was led by Catharina Alberts, PhD, from the World Health Organization’s International Agency for Research on Cancer, and Francesco Negro, MD, emeritus professor, formerly at the Department of Medicine and Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland. The session addressed the potential to lower cancer incidence through enhanced infection prevention and detection strategies.

In 2022, infections were linked to 2.5 million new cancer diagnoses. The primary bacterium involved in carcinogenic infections is Helicobacter pylori. Among viruses, human papillomavirus (HPV), hepatitis B virus (HBV), and hepatitis C virus (HCV) are the most notable. Other viruses are also significant, particularly in individuals living with HIV, but the focus remains on the aforementioned pathogens.

Three primary mechanisms by which these infections lead to cancer were discussed:

• DNA integration into cells: Particularly crucial for HBV and HPV, prevention is possible through vaccination
• Chronic inflammation: Notable in viral hepatitis and H pylori cases, treatable through eradication treatments
• Immune suppression: Significant in HIV cases, which by itself is not carcinogenic but becomes so through coinfections such as HPV, Epstein-Barr virus, and Kaposi sarcoma–associated herpesvirus

Transmission and Impact

H pylori, mainly transmitted through the fecal-oral route, is typically acquired in childhood and can persist in the stomach if untreated. Antibiotic treatment varies globally.

HPV, a sexually transmitted virus, is linked to nearly all cervical cancer cases, 88% of anal cancers, 78% of vaginal cancers, 50% of penile cancers, and 43% of oropharyngeal cancers.

HBV and HCV are confirmed class 1 carcinogens, which means they are confirmed cancer-causing agents. Globally, HBV affects 3% of the population (248 million) and HCV affects approximately 1% (51.3 million), with substantial geographic variation. Cirrhosis-related complications account for 90% of viral hepatitis deaths worldwide, one third of which are due to liver cancer.

Screening and Prevention

Risk stratification strategies have failed to detect most chronic HBV and HCV infections, and the global targets set by the World Health Organization remain unmet. With effective and safe antiviral treatments available, is universal lifetime screening a viable option?

Experts from several countries, including the Centers for Disease Control and Prevention (CDC) in the United States, China, and Australia, have found lifetime screening for hepatitis B in adults to be cost-effective and now recommend it. The CDC also recommends lifetime screening for HCV.

There are clear benefits to universal screening, such as cost savings, effective treatment for HCV, and the simplicity of screening tests, which can be easily included in other ongoing programs. However, there are also important drawbacks. 

The studies supporting this cost-effectiveness are based on predictive models, not real-world data, and do not consider other potential costs, such as awareness campaigns and training of primary care physicians for proper counseling of patients. Another issue is the number needed to treat — how many people need to be screened to identify one case? 

In countries with a high prevalence (> 3%), such as Pakistan or Egypt, approximately 14.2 individuals need to be screened to identify one case. However, when the prevalence is below 3%, even in areas that are highly endemic, the number rises above 200. Additionally, even in countries with sufficient resources, not all detected cases are treated.

Interdisciplinary Collaboration

The speakers questioned whether there was sufficient collaboration between oncology and infectious diseases. With robust prevention tools, such as vaccines, early screening, and early treatment, how can we use them more effectively? How do we address implementation barriers? Future strategies must also consider equity issues. To date, prevention has been based on risk stratification screening, which has proven ineffective. Expanding screening could improve access for the most vulnerable populations. While universal screening is still difficult to justify, integrating screening with other programs might be a feasible option.

This story was translated from Univadis Spain using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.