New Global Study Identifies Infections as Root Cause for One in Eight Cancer Cancers

POLICY WIRE — Geneva — New data released by the World Health Organization (WHO) indicates that approximately 12% of cancer cases globally in 2024 were likely triggered by infections rather than lifestyle choices.

The research, featured in The Lancet Oncology, conducted a deep dive into the prevalence and underlying origins of various malignancies, with a specific focus on the impact of infectious agents.

Researchers identified that 2.3 million new cancer cases were linked to infections. The vast majority of these cases stem from just five specific pathogens: Helicobacter pylori (4%), human papillomavirus or HPV (4%), hepatitis B (2%), Epstein-Barr virus (1%), and hepatitis C (under 1%).

These specific infections are responsible for more than 20 different types of cancer, including conditions affecting the stomach, liver, blood, and cervix.

The team behind the study has spent nearly three decades investigating this medical field, building upon previous analyses of infection-related cancer cases conducted in 1990, 2002, 2008, 2012, and 2018.

While the percentage of cancers caused by infections appears to have declined from a peak of 18% in 2002, the authors note that direct chronological comparisons are difficult due to significant shifts in data quality and reporting sources over the years.

Rather than focusing on historical trend lines, the current report is designed to pinpoint specific areas where aggressive infection control and prevention could significantly lower the global cancer burden.

To understand the link, scientists have mapped the molecular pathways by which infections transform host cells. Viruses can alter cellular genetics directly or indirectly, leading to uncontrolled cell growth.

There are three primary viral mechanisms: first, they can disable a cell’s ability to self-destruct by inactivating the TP53 protein or halt normal division by inactivating the RB protein. Second, they may insert their own DNA into the host cell, disrupting regulatory genes. Third, the virus may carry a cancer-causing gene known as an oncogene.

Viruses are not the only culprits; bacteria like Helicobacter pylori (associated with stomach ulcers) and parasites like Opisthorchis viverrini (a liver fluke) also contribute through indirect means.

These chronic infections cause persistent inflammation, where the body’s immune response becomes overactive, damaging tissues and causing genetic mutations during the rapid cell division required for repair.

While other mechanisms may yet be discovered, the connection between infection and cancer is considered indisputable, highlighting that many cases are potentially preventable. In Australia, the HPV vaccine serves as a primary example of this, protecting against strains linked to cervical cancer.

Senior researchers Eddie La Marca and Sarah Diepstrat from the Eliza Hall Institute of Medical Research noted that since HPV vaccination began in 2007, related infections have plummeted by 90% among eligible populations. This progress puts Australia on course to eliminate cervical cancer by 2035.

However, experts expressed concern as vaccination rates among 15-year-olds dipped from 85.7% in 2020 to 79.5% in 2024. The WHO and Australian authorities target a 90% vaccination rate for 15-year-old girls by 2030.

The study further highlights that 75% of infection-related cancers occur in low- and middle-income nations. Treating conditions like HIV, H. pylori, and hepatitis B and C—along with vaccinations and screenings—is vital, though limited access in poorer regions remains a major global equity challenge.

Reporting by Policy-Wire (PW)